General Cat

[NebulaStilo]

That looks well placed to catch water and dirt. I think a cleanup will help.. particularly if the wiring connection to it is letting in moisture and upsetting the voltage - it doesn't take much to throw out the readings. If you're keeping any of the sensors, it may be worth sticking some silcone sealant at the joint.

Ralf S.

Thanks. Will do that.
I'm getting a P0141 heater malfunction.
Could be dirt clogging it up right?

 

[NebulaStilo]

That looks well placed to catch water and dirt. I think a cleanup will help.. particularly if the wiring connection to it is letting in moisture and upsetting the voltage - it doesn't take much to throw out the readings. If you're keeping any of the sensors, it may be worth sticking some silcone sealant at the joint.

Ralf S.

And it looks pretty far from the hole of the exhaust because look how far out that spacer is. Going to clean it out and give it a try without spacer

 

[NebulaStilo]

That looks well placed to catch water and dirt. I think a cleanup will help.. particularly if the wiring connection to it is letting in moisture and upsetting the voltage - it doesn't take much to throw out the readings. If you're keeping any of the sensors, it may be worth sticking some silcone sealant at the joint.

Ralf S.

Hi Ralf.
So today my father took my mother to the shops with the car and he said the car drove normal. No misfire. The usual hesitation on acceleration we know about from the O2 but no misfire we got while the car stood.
Seems the ECU was throwing in too much fuel into the cylinders upon idle. When you let the car idle abit then it goes away as if the excess fuel was burnt.
When there was misfire on idle the car would have a distinctive fuel smell

 

[Ralf S.]

The heater malfunction is usual for a sensor failure. The heater goes, so the lambda doesn't work very well at low engine speeds, and then if it's too cool, it can collect contamination instead of buring it off, so the lambda sensing elements (just an electrical resistance) can get thrown out.

So, if you're going to change it, that ought to clear up the fault too (though I would remove them prior to changing the sensor, so you can see immediately whether the fault comes back.

I never opened up a lamdba sensor but I guess there's some wire coil/windings to act as the heater. Heaters work by passing a current through a resistance, so if the heat damages the windings that would break the heater. The don't tend to get physically damaged but since they work on a very small range of resistance measurement, anything that upsets the reading can cause problems.

Usually issues come from cheap sensors that are supplied without a plug connector. You have to cut your old wiring and splice the end with the connector on it to the new sensor. Of course, any bad soldering/connection.. or any dirt/moisture in that joint will cause problems later, so it's best to spend a bit extra and get a sensor with a plug attached.

The spacer I don't think is a problem. It looks designed to stand-off the sensor from the exhaust manifold, to avoid heat damage to the wiring. If you remove the spacer, a duff sensor might start working better, since the heater not working doesn't matter, all of a sudden... but longer term, the wiring insulation may melt/short out.. so if Fiat (who might know something about it) went to the trouble of adding a sensor, then it's maybe best if you keep yours on there.

Ralf S.

 

[NebulaStilo]

The heater malfunction is usual for a sensor failure. The heater goes, so the lambda doesn't work very well at low engine speeds, and then if it's too cool, it can collect contamination instead of buring it off, so the lambda sensing elements (just an electrical resistance) can get thrown out.

So, if you're going to change it, that ought to clear up the fault too (though I would remove them prior to changing the sensor, so you can see immediately whether the fault comes back.

I never opened up a lamdba sensor but I guess there's some wire coil/windings to act as the heater. Heaters work by passing a current through a resistance, so if the heat damages the windings that would break the heater. The don't tend to get physically damaged but since they work on a very small range of resistance measurement, anything that upsets the reading can cause problems.

Usually issues come from cheap sensors that are supplied without a plug connector. You have to cut your old wiring and splice the end with the connector on it to the new sensor. Of course, any bad soldering/connection.. or any dirt/moisture in that joint will cause problems later, so it's best to spend a bit extra and get a sensor with a plug attached.

The spacer I don't think is a problem. It looks designed to stand-off the sensor from the exhaust manifold, to avoid heat damage to the wiring. If you remove the spacer, a duff sensor might start working better, since the heater not working doesn't matter, all of a sudden... but longer term, the wiring insulation may melt/short out.. so if Fiat (who might know something about it) went to the trouble of adding a sensor, then it's maybe best if you keep yours on there.

Ralf S.

Thanks Ralf.
I'm pricing a few sensors from local online stores here so the shipping fee won't be hectic.
From fiat itself the sensor comes to R1700 which isn't a little money since work has been put on hold. This was going to be the month where I sort out the car but God has other plans.

Just a quik question,why does the car accelerate way better at night or when the air outside is cold?

Thanks

 

[NebulaStilo]

The heater malfunction is usual for a sensor failure. The heater goes, so the lambda doesn't work very well at low engine speeds, and then if it's too cool, it can collect contamination instead of buring it off, so the lambda sensing elements (just an electrical resistance) can get thrown out.

So, if you're going to change it, that ought to clear up the fault too (though I would remove them prior to changing the sensor, so you can see immediately whether the fault comes back.

I never opened up a lamdba sensor but I guess there's some wire coil/windings to act as the heater. Heaters work by passing a current through a resistance, so if the heat damages the windings that would break the heater. The don't tend to get physically damaged but since they work on a very small range of resistance measurement, anything that upsets the reading can cause problems.

Usually issues come from cheap sensors that are supplied without a plug connector. You have to cut your old wiring and splice the end with the connector on it to the new sensor. Of course, any bad soldering/connection.. or any dirt/moisture in that joint will cause problems later, so it's best to spend a bit extra and get a sensor with a plug attached.

The spacer I don't think is a problem. It looks designed to stand-off the sensor from the exhaust manifold, to avoid heat damage to the wiring. If you remove the spacer, a duff sensor might start working better, since the heater not working doesn't matter, all of a sudden... but longer term, the wiring insulation may melt/short out.. so if Fiat (who might know something about it) went to the trouble of adding a sensor, then it's maybe best if you keep yours on there.

Ralf S.

What's your take on a 100% working sensor? Someone stripping a stilo that will sell the part to me. He says it's working 100%

 

[Ralf S.]

Thanks Ralf.
I'm pricing a few sensors from local online stores here so the shipping fee won't be hectic.
From fiat itself the sensor comes to R1700 which isn't a little money since work has been put on hold. This was going to be the month where I sort out the car but God has other plans.

Just a quik question,why does the car accelerate way better at night or when the air outside is cold?

Thanks

Depending on the difference between the temperatures and your altitude above sea level, it could be down to the charge density. When it's cold the air is more dense, so it has more oxygen in it (not a different ratio of oxygen, just more in the same volume of air), so your car will be able to squirt more petrol in there to take advantage of it.

If you're at high altitude and the difference between night and day is -5C to +40C, the difference will be bigger and you'll notice it more than if the night time temperature is just a few degrees cooler than the daytime (as in the UK for instance).


Ralf S.

 

[Ralf S.]

What's your take on a 100% working sensor? Someone stripping a stilo that will sell the part to me. He says it's working 100%

Electronic sensors are worth about 5 Loti.. since there's no way to tell by looking at them (unless they are crushed or have pieces missing) whether they are any good or not.

But as my mechanic once said about an engine I was after, "it was running okay when the car it was in hit the tree.." so there's a chance that it's good.

If it's not tooooo dear and you think it's worth taking a chance with it, I'd say it's worth it. Even if it's not great, it might change how your car runs, so you'll be more confident that a new one will definitely fix your problem. If it makes no difference at all to your car then it might hint that your problem is not the lambda (though what...?) since it's unusual for two failed sensors to give *exactly* the same failure.

Offer him a bag of chips and see if he'll let you have it.. He'll have a job shifting it anytime soon..


Ralf S.

 

[NebulaStilo]

Electronic sensors are worth about 5 Loti.. since there's no way to tell by looking at them (unless they are crushed or have pieces missing) whether they are any good or not.

But as my mechanic once said about an engine I was after, "it was running okay when the car it was in hit the tree.." so there's a chance that it's good.

If it's not tooooo dear and you think it's worth taking a chance with it, I'd say it's worth it. Even if it's not great, it might change how your car runs, so you'll be more confident that a new one will definitely fix your problem. If it makes no difference at all to your car then it might hint that your problem is not the lambda (though what...?) since it's unusual for two failed sensors to give *exactly* the same failure.

Offer him a bag of chips and see if he'll let you have it.. He'll have a job shifting it anytime soon..


Ralf S.

Thanks for both replies. Appreciate it.

So yeah,it makes sense what you're saying.

Once i get some money I'll go and buy it. Hes in a different province to me(ie different state)
Drove the car myself today to my parents place because our laws now are that we can move around. So my partner and I going to have a bbq here.

Anyway the car drove the usual. Hesitation seems to be getting worse. Didnt want to drive her hard though. On pull away she's very lazy but once in high gears she's going nice but also lazy to over take also. So basically a weak acceleration. Seems weaker than before though.

 

[NebulaStilo]

Depending on the difference between the temperatures and your altitude above sea level, it could be down to the charge density. When it's cold the air is more dense, so it has more oxygen in it (not a different ratio of oxygen, just more in the same volume of air), so your car will be able to squirt more petrol in there to take advantage of it.

If you're at high altitude and the difference between night and day is -5C to +40C, the difference will be bigger and you'll notice it more than if the night time temperature is just a few degrees cooler than the daytime (as in the UK for instance).


Ralf S.

Make sense since it seems sometimes and more often the car over fuels. Hence a strong fuel smell at idle and revving. So like you say there is more oxygen in the air at low temp which is allowing the car to burn the fuel ratio better.
Am I correct??

 

[NebulaStilo]

Electronic sensors are worth about 5 Loti.. since there's no way to tell by looking at them (unless they are crushed or have pieces missing) whether they are any good or not.

But as my mechanic once said about an engine I was after, "it was running okay when the car it was in hit the tree.." so there's a chance that it's good.

If it's not tooooo dear and you think it's worth taking a chance with it, I'd say it's worth it. Even if it's not great, it might change how your car runs, so you'll be more confident that a new one will definitely fix your problem. If it makes no difference at all to your car then it might hint that your problem is not the lambda (though what...?) since it's unusual for two failed sensors to give *exactly* the same failure.

Offer him a bag of chips and see if he'll let you have it.. He'll have a job shifting it anytime soon..


Ralf S.

Hi Ralf.
So bored as I am I was going through the net ans decided to read up on knock sensors. I see they have very similar faulty symptoms to an O2 sensor.
Whats the chance its a knock sensor kicking out a O2 fault? I'm just playing devil's advocate?

 

[Ralf S.]

I’d say low very little.

You might get the same driving symptoms but the code fault comes from the ECU monitoring what the sensors are telling it. Each sensor had a range of signals it returns and as soon as one gives no signal or a signal that’s too high or too low for what should be happening, the ECU asks for you to work out what’s happening via an error code.

A knock sensor would have its own ID code, so you would have a different stored code. But Apart from all that, I don’t think a Stilo has a knock sensor.

Ralf S.

 

[NebulaStilo]

I’d say low very little.

You might get the same driving symptoms but the code fault comes from the ECU monitoring what the sensors are telling it. Each sensor had a range of signals it returns and as soon as one gives no signal or a signal that’s too high or too low for what should be happening, the ECU asks for you to work out what’s happening via an error code.

A knock sensor would have its own ID code, so you would have a different stored code. But Apart from all that, I don’t think a Stilo has a knock sensor.

Ralf S.

The 1.6 has one. I still saw a diagram on the forum.

But thank you for the reply. I was also thinking if it is a knock sensor then I wouldve had some sort of ID code coming from sensor or pointing towards it.

 

[NebulaStilo]

I’d say low very little.

You might get the same driving symptoms but the code fault comes from the ECU monitoring what the sensors are telling it. Each sensor had a range of signals it returns and as soon as one gives no signal or a signal that’s too high or too low for what should be happening, the ECU asks for you to work out what’s happening via an error code.

A knock sensor would have its own ID code, so you would have a different stored code. But Apart from all that, I don’t think a Stilo has a knock sensor.

Ralf S.

Hi.
So I removed both sensors and gave them a clean. They were seriously dirty!! A huge amount of carbon build up came out. I removed spacer and even the probe was covered in carbon so much that I couldn't see the actual part. Cleaned it off nicely. Pre CAT I removed as well and gave a good clean,he was too covered in carbon.

Cleared fault and checked pending faults and sensor 2 came back up. No check engine just yet as its not yet stored. Car doesn't seem to idle better. I will be driving her tommorow so will feel how she drives.

Carbon on both O2 sensors,whats the cause of that? Dirty valves?

 

[NebulaStilo]

I’d say low very little.

You might get the same driving symptoms but the code fault comes from the ECU monitoring what the sensors are telling it. Each sensor had a range of signals it returns and as soon as one gives no signal or a signal that’s too high or too low for what should be happening, the ECU asks for you to work out what’s happening via an error code.

A knock sensor would have its own ID code, so you would have a different stored code. But Apart from all that, I don’t think a Stilo has a knock sensor.

Ralf S.

Besides both sensors having a huge amount of carbon build up. Sensor 2 has a open white wire join. Something I didn't do. Previous owner caught on such bull. I checked and wires connected just exposed. Closed it up.
Im getting a P0141. Heater circuit and white wire is the heater. Mmmm. Maybe I'll do some wire crimping

 

[Ralf S.]

Hi.
So I removed both sensors and gave them a clean. They were seriously dirty!! A huge amount of carbon build up came out. I removed spacer and even the probe was covered in carbon so much that I couldn't see the actual part. Cleaned it off nicely. Pre CAT I removed as well and gave a good clean,he was too covered in carbon.

Cleared fault and checked pending faults and sensor 2 came back up. No check engine just yet as its not yet stored. Car doesn't seem to idle better. I will be driving her tommorow so will feel how she drives.

Carbon on both O2 sensors,whats the cause of that? Dirty valves?

Carbon on the sensors means that the engine is running too rich. The problem might be that the lambda's aren't working properly, so are confusing the ECU or there is/was a problem with the MAF which caused a lot of carbon which may have damaged the lambda sensors.

If you have a heating fault with the lambda sensor it suggests that the heater packed up, which could have thrown out the sensor's readings, which would have led to morr carbon, which would have been more likely to stick to the sensor since it was unable to keep itself clean.

Get rid of the sensor with the cut wires. The previous owner may have tried to repair the circuit if the wire looked damaged, whereas the sensor itself is likely knackered and there's not much to be done with it.

If you have a poor connection, there's also more chance that the signal voltage will be affected by passing through the joint, which will upset the ECU, even if the lambda itself is fine.

Ralf S.

 

[NebulaStilo]

Carbon on the sensors means that the engine is running too rich. The problem might be that the lambda's aren't working properly, so are confusing the ECU or there is/was a problem with the MAF which caused a lot of carbon which may have damaged the lambda sensors.

If you have a heating fault with the lambda sensor it suggests that the heater packed up, which could have thrown out the sensor's readings, which would have led to morr carbon, which would have been more likely to stick to the sensor since it was unable to keep itself clean.

Get rid of the sensor with the cut wires. The previous owner may have tried to repair the circuit if the wire looked damaged, whereas the sensor itself is likely knackered and there's not much to be done with it.

If you have a poor connection, there's also more chance that the signal voltage will be affected by passing through the joint, which will upset the ECU, even if the lambda itself is fine.

Ralf S.

Hi thanks for the reply

So I do have a heater malfunction on sensor 2.
No MAF on the car. Only a MAP.
On my scan tool I have a connection to sensor. Ie the ECU is picking up the sensor. But I'm getting no reading. Just a green connected status.

Does sensor 2 affect the cars driving? I read some sensors only monitor CAT efficiency

 

[NebulaStilo]

Carbon on the sensors means that the engine is running too rich. The problem might be that the lambda's aren't working properly, so are confusing the ECU or there is/was a problem with the MAF which caused a lot of carbon which may have damaged the lambda sensors.

If you have a heating fault with the lambda sensor it suggests that the heater packed up, which could have thrown out the sensor's readings, which would have led to morr carbon, which would have been more likely to stick to the sensor since it was unable to keep itself clean.

Get rid of the sensor with the cut wires. The previous owner may have tried to repair the circuit if the wire looked damaged, whereas the sensor itself is likely knackered and there's not much to be done with it.

If you have a poor connection, there's also more chance that the signal voltage will be affected by passing through the joint, which will upset the ECU, even if the lambda itself is fine.

Ralf S.

Hi Ralf.
So I plugged my scan tool in and checked real time data.
02 bank 1 sensor 2 isn't picking up. See in the pics that it's connected but not reading anything. Sensor 1 is giving readings but at idle it's jumping around and on a rev it's fairly stable at around 0.7. Is this correct or what?

Also the real time data I screenshot is showing the car is in closed loop using 1 o2 sensor. Check the pic.
Pleade give your advice on this.
Thank you

 

[NebulaStilo]

Carbon on the sensors means that the engine is running too rich. The problem might be that the lambda's aren't working properly, so are confusing the ECU or there is/was a problem with the MAF which caused a lot of carbon which may have damaged the lambda sensors.

If you have a heating fault with the lambda sensor it suggests that the heater packed up, which could have thrown out the sensor's readings, which would have led to morr carbon, which would have been more likely to stick to the sensor since it was unable to keep itself clean.

Get rid of the sensor with the cut wires. The previous owner may have tried to repair the circuit if the wire looked damaged, whereas the sensor itself is likely knackered and there's not much to be done with it.

If you have a poor connection, there's also more chance that the signal voltage will be affected by passing through the joint, which will upset the ECU, even if the lambda itself is fine.

Ralf S.

Hi

I also had a look at the wiring again. I found grey was completely disconnected and white was connected badly. I reconnected them both and cleared code. It didn't bring up a CEL again but a pending fault returned again P0141. Could bad ground have destroyed the heater?

 

[Ralf S.]

Until you get a working sensor in there it's going to be fruitless looking too deeply into the error codes, since they could be caused by something else, rather than the headline message. E.g. if a sensor is not properly connected, then you may get an error code saying that the sensor is faulty, whereas it would just need re-connecting.

In your case, the sensor sounds like it's not working. If you have cleaned it up and firmly re-attached the wiring and re-set the codes then that ought to have solved the problem, if the sensor was not faulty...

So it sounds like the sensor has failed (like light bulbs, they can just die eventually) and a previous owner has tried different remedies which involved cutting/re-connecting the wiring, which you found to be in bad shape.

Somewhere on the relay board (unfortunately I don't know Stilo's electrics that well) will be a relay that controls the lambda heater circuit. If you can track that down and make sure it's spotlessly clean and working (you'll need to test the voltage across the heater circuit) then that might be the last place that's causing a problem that is not the lambda sensor itself... but presuming that your atmosphere is dry and there's no green corrosion around the relay board connections, then the actual sensor is still the more likely culprit.

Did you get hold of the second-hand one?


Ralf S.