Technical Open-loop post-cat o2

[brinker]

My post-cat o2 sensor comes back as open loop in MES but doesn't post error code or EML - shouldn't it? Car seems to be running fine...

 

[varesecrazy]

I THINK it's just wasting fuel = slow to warm engine

but maybe the pre-cat is doing an OK job..,

 

[atom0007]

Should go closed loop when warm. Is your engine up to temperature?

 

[brinker]

Should go closed loop when warm. Is your engine up to temperature?

I checked it at 63° - which is 20 below normal operating temp. I'd have expected it to be under normal conditions by that temp, but perhaps that isn't the case, and it is still running a warm-up?

 

[atom0007]

I don't know the lower trigger point, check it after a run to see if it closes. Certainly, at the start with a cooler engine it is open loop

 

[portland_bill]

If it is the O2 sensor heating circuit that is faulty, the sensor will just heat up slower, so taking longer to give readings that will reduce fuel consumption.
If the output voltages were incorrect, I'd expect a warning light on.
Time to replace it sometime. Might be an idea to replace both, prevention...etc.

 

[brinker]

If it is the O2 sensor heating circuit that is faulty, the sensor will just heat up slower, so taking longer to give readings that will reduce fuel consumption.
If the output voltages were incorrect, I'd expect a warning light on.
Time to replace it sometime. Might be an idea to replace both, prevention...etc.

It's not the heater than comes back as open-loop, it's the sensor itself. Voltage shows 0.0000v. I will check it at running temp at my next convenience.

 

[judderbar]

MES does not show my Oxygen sensors correctly

I have ME73H4F001 ECU

 

[Ziggy122]

Understand the phrase

Open loop Readings = The ECU recieves the signal from the Sensor - but ignores it
it doesn't want it - it'll ignore it

Closed Loop = ECU recieves Signal - ECU processes data recieved - ECU outputs to required Devices (coils / injectors etc) - ECU Recieves new signal and repeat

The POST CAT sensor is After Catalystic convertor
The Cat takes time to warm up, before it becomes efficient
So the ECU keeps it in open look till it thinks its warmed up (timer or engine temperature reading)
The Heater elements DONT HELP THE CAT WARM UP
The Heater elements Help the Sensor React better to the flow of emissions

Even so - the post sensor once warmed shouldnt give a Null reading (0.0000v)
UNLESS you are of the many punto's that doesn't even have a post cat sensor
2003 onwards went to EURO 4 emiision regs so it got the cam and post cat sensor to help lower emiisions

Ziggy

 

[brinker]

Understand the phrase

Open loop Readings = The ECU recieves the signal from the Sensor - but ignores it
it doesn't want it - it'll ignore it

Closed Loop = ECU recieves Signal - ECU processes data recieved - ECU outputs to required Devices (coils / injectors etc) - ECU Recieves new signal and repeat

The POST CAT sensor is After Catalystic convertor
The Cat takes time to warm up, before it becomes efficient
So the ECU keeps it in open look till it thinks its warmed up (timer or engine temperature reading)
The Heater elements DONT HELP THE CAT WARM UP
The Heater elements Help the Sensor React better to the flow of emissions

Even so - the post sensor once warmed shouldnt give a Null reading (0.0000v)
UNLESS you are of the many punto's that doesn't even have a post cat sensor
2003 onwards went to EURO 4 emiision regs so it got the cam and post cat sensor to help lower emiisions

Ziggy

Mine is an '05 so I've got both. I did a quick check when I got home today, after a 15 minute drive, so water temp was as it should be, but post-cat o2 still comes back open-loop. I did however post 0.0046v reading in idle, so it is working after all.

 

[Ziggy122]

Swap post and pre cat sensors over
There the same sensor
If the sensor thats giving poor/low voltage reading is still in the new place and the other one is giving a reading then its a duff sensor

Ziggy

 

[s and b]

Swap post and pre cat sensors over
There the same sensor
If the sensor thats giving poor/low voltage reading is still in the new place and the other one is giving a reading then its a duff sensor

Ziggy

good advice
this is exactly what i used to do if it was showing as a lazy lambda post cat

 

[brinker]

Yeah, will probably try that this weekend, see what happens

 

[brinker]

Seems as though I get fully normal readings on both o2 sensors, have swapped them around earlier today.