Evening guy's

Yesterday afternoon I got an ECU warning light appear on the dashboard, but being in the middle of the M4 travelling home, I used my Torque application on my Samsung mobile to get the fault code, and it returned with P0130 - o2 sensor, bank 1 sensor 1.

Now at the moment, the only thing I can physically tell what's wrong with the car is a hesitation in accelerating, but it's minimal, and is not really affecting the day to day use. I'm sure I had this fault around the same time last year, but without the warning light, and again same sort of physical driving problems.

So this evening, again using my torque app on my phone, I have checked the voltage at both sensors, and they are reading 0.43v to 0.45v at sensor 1, and 0.47v to 0.49v at sensor 2.

I've had this car from new (2006 3dr Stilo Blue) and I don't think this car has had a Lambda sensor replacement (unless done on a service), so I can only assume It's the sensor(s) that's playing up. Would this be a fair assumption.

If you were viewing a trace of your precat O2 sensor (and not just using a multimeter) and it was just staying around 0.45v at idle and the engine was warm then there's definitely something wrong with it. It should be oscillating somewhere between 0.1v and 0.9v every second on a warm engine tickover

Symptoms are poor mpg, unsteady idle and poor pick up from low rpm so it sounds like your OBD is on target

Deckchair5 said:

If you were viewing a trace of your precat O2 sensor (and not just using a multimeter) and it was just staying around 0.45v at idle and the engine was warm then there's definitely something wrong with it. It should be oscillating somewhere between 0.1v and 0.9v every second on a warm engine tickover

Symptoms are poor mpg, unsteady idle and poor pick up from low rpm so it sounds like your OBD is on target

Click to expand...

Poor MPG is a definite issue, the car at present having done 160 miles home (on a full tank) from Wales yesterday, you would think the fuel would have leaned off during the journey, so now with half a tank of fuel remaining, range to empty is saying 180 miles, when previously It has said anywhere between 230 and 270 miles to empty.

Unsteady idle not been an issue for me thankfully.

Poor pick-up, or more of a hesitation I have had, and has been around before. I've not noticed it this evening, everything seems fine at the moment.

I have stored the fault on my mobile for future info, and proceeded to clear the warning light off the dash using my Torque application on my phone, so all is back to normal until it bites me in the arse once again.

My money is on the Lambda sensor(s) being faulty, but with the festive season approaching at a rate of knots, I'm going to put it off until either the festive season is over or the car dies completely. I've priced up 2 new sensors for my car off flea bay for around £110 with postage, so I have some work cut out for myself in the new year.

EDIT:
Just found the locations of the Lambda sensors using ePER, and it seems to be a lot easier than first thought, so may just bite the bullet, get 2 new probes and fit them before winter takes a hold good and proper. I thought it was going to be an under car excursion to replace these items.

The pre cat sensor is real easy on the 1.6 and if you're burning 30% extra fuel then it soon pays for itself

Deckchair5 said:

The pre cat sensor is real easy on the 1.6 and if you're burning 30% extra fuel then it soon pays for itself

Click to expand...

Is the 1.4 similar in design? that's the engine fitted to the Stilo Blue editions.

Yes, very similar.

As the precat sensor does almost all the work, will give you much better economy and is the only one being flagged by your OBD at the moment then, especially if money is tight, then you might want to change just that one for the moment and see what the OBD thinks then. The post cat sensor is largely checking the efficiency of the cat. I've no idea why your post cat O2 sensor is seemingly flat lined too but I would just change the front one for now and then check the effect of that on the post cat sensor output

Remember they have to be fully warmed up to operating temperature to work

Well the same code has once again re-appeared followed by the associated ECU warning light, and has again pin pointed the same sensor.

Question I have is, what is the best sensor to get? I'm looking at the Bosch LS6206 for £55.43 including postage from ebay, would this a good replacement probe?

if youre any good with a soldering iron you can get 'generics' for half that money that do exatly the same job... It all depends on your budget

denso
bosch
NGK

all much of a likeness really apart from price

Fiat p/n :- 46762182

richydraper said:

if youre any good with a soldering iron you can get 'generics' for half that money that do exatly the same job... It all depends on your budget

denso
bosch
NGK

all much of a likeness really apart from price

Click to expand...

Yeah saw something similar around the web. Price is not really relevant (although purse strings are getting rather tight!), and piece of mind can be had if money is spent wisely

I'm still seeing variation in the voltage produced by the probe whilst driving home from work this evening, my torque app has indicated the voltage had varied between 0.36v to 0.52v on sensor 1, and am assuming the voltage is doing something similar on sensor 2, although not monitored by me.

I think the ECU warning light is being kicked up by the computer because the probe is becoming unstable, even though it's still functioning. My early indication the warning was going to pop up again was my low range to empty, and with just under half a tank of fuel remaining, 113 miles to empty is definitely not right, It would normally be around 230 miles

my post cat lambda has an intermittent fault it seems the voltage momentarily drops off indicating a break down of the sensor... its not bothering me too much partly because i know it works a majority of the time the readings dont have to be far out for it to throw a fault but iirc it has to happen a set number of times before it logs a fault and throws a MIL

afaik its overfueling cos its picking up a fault on that sensor (its better to run rich than lean) hence the drop in MPG altho im sure if im wrong someone will set the record straight!

my torque app has indicated the voltage had varied between 0.36v to 0.52v on sensor 1
That's still not good or normal voltages for sensor 1. It should swing from around 0.1 v to 0.9v as posted previously so it's not working properly

Back probe the sensor connector signal wire (usual coloured black) and check the voltage directly. between there and earth


It should look like this


Here I'm checking out a good O2 sensor. You can see it has a quick response and goes from around 0.1v to 0.9v so this one is good to go

Well I decided to order my new sensor from Motor parts direct, and cost me £52 including delivery, and I have also ordered a new multimeter after months and months of putting it off (old one broke) from amazon.

I will do the same check with the multimeter on the sensor currently fitted before I remove it, and see how its working.

Does anyone have any suggestions on how to remove the old sensor should it be faulty, any tips & tricks would be helpful.

If you're going to take the old one out and bin it regardless then you can chop off the wires and put a socket or ring spanner on it. If you're going to replace it with a universal sensor then chop the wires close to the old sensor

To take it out with minimal damage and to help insert the new one with wires attached then it's best to obtain the proper lambda sensor socket with the slit up the side. You can get them at all major motor factors or eBay

Well just checked the sensor this morning now my multimeter has turned up, and yes, my torque app was spot on, the lambda sensor (pre) measured 0.423v +/- 0.03v while running cold. Hopefully I can get this fixed as soon as my new probe turns up.

I did as you instructed Deckchair, put the black probe onto the black wire, and other end on earth (battery terminal) and the multimeter came forth with a reading!

the lambda sensor (pre) measured 0.423v +/- 0.03v while running cold.
OK that's good but you need to check the signal output with engine running and warmed up by at least a few minutes otherwise the sensor won't be hot enough. I expect it will be the same and non responsive from what you were saying before from your Torque app readings. The sensor has an integral heater element and that might be bad, they often break. You can check for just a circuit of just a few ohms resistance though the heater wires now you have a multimeter (usually both coloured white) and you can check for 12v across the heater wires when it's installed

You see how hot I've made the sensor in the above video, glowing red at the tip? It needs to up near those temperatures otherwise it will be non operational

I'm sure the new sensor will give you some much livelier readings and it will improve your fuel consumption by using sometimes 1/3 less fuel so it will pay for itself in no time

Are they both white wire's? I recall seeing black (1st), grey (2nd) and a white (4th), the 3rd wire I'm not sure what the colour is, will check in the morning. at the moment, I'm trying to calm down 2 dogs, stop a little one crying and kick off a cat that's walking between my legs because she's not sure what all the noise is! Don't you just love bonfire night!

O2 sensors come in an interesting variety of wire colours, some have 3 wires and some have 4 but black is almost always the signal, the two heater wires are both the same colour (often white) and the earth will be whatever is remaining (more often grey)

I'm lucky, my labrador is too laid back to be bothered by the firecrackers

Well just checked the resistance on the sensor, and it's coming back with 9 ohms, and from what i've read elsewhere, thats about normal, so I can eliminate the heater element.

How do I check for 12v? do i do it with the engine running? or unplug it and check it through the connector?

Well my new lambda probe has turned up after a delay with shipping, and it's one that needs crimping onto the original plug, although it does state it's a Bosch sensor.

I'm hoping to use this free weekend to get the probe changed, but I still want to do a final check on the one currently fitted. What I want to know is, how do I measure 12v on the sensor.

Just as you might expect, check the voltage between the two heater wires with engine running. You can slide 2 pins down the back of the connector and connect to them