[GC1980]

Which brand and or part number should I be looking for to replace my post cat sensor?

Thanks.

 

[George1]

Which brand and or part number should I be looking for to replace my post cat sensor?

Thanks.

Is it switched on in your map? I've got a Delphi post cat lambda but it's switched off as the high flow cat kept putting the engine light on. My pre cat is a Bosch

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[E-R53]

Personally, for O2 sensors I would only use NTK or Bosch.

 

[GC1980]

Is it switched on in your map? I've got a Delphi post cat lambda but it's switched off as the high flow cat kept putting the engine light on. My pre cat is a Bosch

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I'm decat, and presumably nothing was coded out for that. Pre cat is Bosch, but Bosch don't do the post cat so I was wondering which one to go for. I've since seen NTK, Delphi and a genuine item on eBay (£225!). Will probably do NTK at £88.

 

[George1]

I'm decat, and presumably nothing was coded out for that. Pre cat is Bosch, but Bosch don't do the post cat so I was wondering which one to go for. I've since seen NTK, Delphi and a genuine item on eBay (£225!). Will probably do NTK at £88.

If you're running a decat then it's definitely coded out. It won't be doing anything. The only function of the post cat is to tell the ECU if the cat is working or not. All your fuelling is controlled by the pre cat. It might throw a light on if it's gone open circuit but that's all.

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[GC1980]

If you're running a decat then it's definitely coded out. It won't be doing anything. The only function of the post cat is to tell the ECU if the cat is working or not. All your fuelling is controlled by the pre cat. It might throw a light on if it's gone open circuit but that's all.

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Interesting, I didn't know that. Maybe then as you say it's gone open circuit? I'd like to get rid of the EML light if I can too. I've a new ventilation tank valve to fit as this also keeps popping up.

 

[George1]

That's just telling you that the heater in the lambda isn't heating up for some reason. I would try and fix it rather than code it out as it might be pulling the voltage down elsewhere. It could be the lambda sensor or more likely a dodgy connection somewhere. Clear the code first if you can, take the leads off the battery terminals and touch them together incase it's a spurious code that's stuck in the EEPROM, unplug the the harness from the lambda and unplug the ECU and check the connections. Give anything a clean that looks like it needs it and put it back together.

Does the code appear with the lambda unplugged?

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[E-R53]

IIRC the sensor heater is separately fused & powered through a relay.

Worth a look.

 

[GC1980]

That's just telling you that the heater in the lambda isn't heating up for some reason. I would try and fix it rather than code it out as it might be pulling the voltage down elsewhere. It could be the lambda sensor or more likely a dodgy connection somewhere. Clear the code first if you can, take the leads off the battery terminals and touch them together incase it's a spurious code that's stuck in the EEPROM, unplug the the harness from the lambda and unplug the ECU and check the connections. Give anything a clean that looks like it needs it and put it back together.

Does the code appear with the lambda unplugged?

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Thanks George, it has crossed my mind it might be a dodgy connection which I guess is going to be tricky to track down?

I have unplugged the harness before and it didn't make any difference but willing to try again. I'll do the ECU too. I've not unplugged it and then run the diagnostic so I'll do that too.

Interestingly the last few days I've not had my OBD2 reader in the car, I swapped it to our X5 and forgot to put it back, but driving the mini it started to drive different and the afr guage idling much higher at 15.6.
Put the dongle in last night and scanned it and this code came up. P2626. So that's now pointing to lambda 1 but it's a relatively new Bosch sensor.

I'm presuming all of this is linked into the fact that when you get on it for even a short period of time it starts to run rough and show it's running lean before it sorts itself out 30 seconds or more later.

I might just book it back in with 1320 and get them to look at it because for the millionth time I can't book a track day until this gets sorted. Quite annoying!

 

[GC1980]

Quick scan: codes shown

Fuel tank breather valve fitted and codes cleared and left with this. Have a new sensor so will aim to get that fixed next. Then the FRM module bla bla bla never ends!

 

[George1]

If be surprised if some of this wasn't related. Is it likely that all of these things have failed at the same time? With a pile of codes like that I would start to suspect wiring or an ECU fault. What a time you're having with that bloody car!

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[GC1980]

If be surprised if some of this wasn't related. Is it likely that all of these things have failed at the same time? With a pile of codes like that I would start to suspect wiring or an ECU fault. What a time you're having with that bloody car!

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Well I've experienced these symptoms a few months after the tuning from 1320. Absolutely not suggesting it's down to them, more to point out I've been managing these symptoms for a while. As it's mostly a daily driver getting to hit boost for flat out sections in London never really triggers anything, it's just those trips out with the boys or some motorway blasts it starts to throw a wobbly. The next drive out I'm going to try and induce the poor running and hit the datalog button to see if that shows up anything.

It's hard to recall the order of codes but I don't think it was all at once. The last thing I changed was the lambda 1, which improved things. But didn't stop everything. Now it's showing again. Not impossible for it to have failed but unlikely I think.

Didn't get a chance to do the ECU reset or battery terminals today but tomorrow I have time. Is there a set time to disconnect the ECU? I've read the battery only needs the earth cable removed, what happens by touching both the terminal wires?

 

[E-R53]

What make of lambda sensor did you use?

I ask as I only ever trust NTK or Bosch at a push as every other brand I have tried has failed early.

I don't think the battery terminal thing does anything at all, but could be wrong.

 

[GC1980]

What make of lambda sensor did you use?

I ask as I only ever trust NTK or Bosch at a push as every other brand I have tried has failed early.

I don't think the battery terminal thing does anything at all, but could be wrong.

It's Bosch for sensor 1 off the turbo, and the replacement for sensor 2 which is yet to be installed is NTK.

I'll get the car on a mates snapon today too and hopefully get a deeper look into codes. The screenshot is from this morning.

 

[George1]

I don't think the battery terminal thing does anything at all, but could be wrong.

It's something that works sometimes if you're writing a new file and there's a code stuck in the EEPROM or you're having problems communicating. It's just to make sure that all the capacitors in the ECU are fully discharged.

It can also get rid of ghost codes that show up after you've deleted something but you can't clear them. I thought maybe the code for sensor 2 wasn't really there but was stuck due to the deletion of the sensor but it's unlikely as the code seems to clear sometimes and come back.

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[E-R53]

Sorry, yes I was talking about stored codes rather than pending ones.

 

[GC1980]

So I got the time to do some more checks as per George's suggestions.

Used my mates snapon tool for something a bit more reliable. These were all the codes so far.. it's a long list. I have possibly not reconnected a sensor for the abs after the bumper had been off to set the bodywork up after the install if the castor bushes.

I cleared the codes, disconnected the battery, touched the terminal leads together. Refitted the terminals and plugged it back in for a scan. These were what was left.

 

[GC1980]

As you can see a lot of codes went, some still remain and I'm aware of what they are to do with. It needs a new harness to the power steering rack for one, I cracked a connector when removing the subframe but superglued it (probably damaged and needs replacing) abs sensor as mentioned earlier on the drivers side I think is either loose or possibly not connected. But after a short drive the lambda came back. This is the screen shot from Dash command.

So I presume that both leads to be replaced should resolve that situation. Other than that I'm out of ideas save for a possible wiring short somewhere 🫣

 

[George1]

Have you checked the wiring for continuity between the ECU and the O2 sensors? Also the supply voltage to the heater circuits. Not sure what it should be but I could look it up on Autodata

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[GC1980]

Have you checked the wiring for continuity between the ECU and the O2 sensors? Also the supply voltage to the heater circuits. Not sure what it should be but I could look it up on Autodata

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I wouldn't even know where to begin with that George. I can see what happens with new leads and if it persists then I'll clearly need to explore the wiring further. I say "I", more like I'll book it in with Millsys or 1320.