Lambda sensors

[Simiewimie]

Had the engine light come on today. Was running fine but when I did a scan it came up with 002C9C, 002C9D, 002C9E, and 002C9F.



Has anybody else had the same? Is it a case of needing to replace the sensors, or is there something else worth checking on first?

Worth mentioning I did have the intake manifold and bits off last Friday to replace the knock sensors, and have done around 100+ miles before this came up, but I don’t think there is anything in that process that would be linked to the sensors?

Thank you for any advice.

 

[Simiewimie]

Well, I replaced the sensors that are in the engine bay (the pre cat ones?) as they are pretty easy to get to and replace. I then replaced the blown 30A fuse in engine bay fuse box, cleared the codes, started the engine, and crossed my fingers... b***ard problem still there.
Same codes as well.
Now thinking it's maybe the other sensors that are harder to get to causing the problem? In which case it is going to be in to the local garage, as it looks a bit of a pig of a job.
Was really hopeful it was going to be down to the top sensors. Ah well, at least I have nice shiny new ones.

 

[enuff_zed]

I think it would be very odd for all the sensors to fail at once.
I think if it were me I would be looking at some part of the engine system that is common to both banks. Something on the intake side.
Air leak, MAF etc.
As is usual with faults like this, if you did something and now there's a problem then chances are it's something you did.
In this case, even after 100 miles I think it could be a wrongly seated intake pipe.
As [ref]colb[/ref] has to keep repeating, if you have an air leak then the DME tries to compensate by richening the mixture. Eventually it can't richen it any more and throws up Cat sensor faults. My guess is it maybe takes about 100 miles to get to that point. :wink:

BTW, I missed your original post and it looks like everyone else did as well, otherwise you would have received this advice before you wasted your money.

 

[Simiewimie]

I think it would be very odd for all the sensors to fail at once.
I think if it were me I would be looking at some part of the engine system that is common to both banks. Something on the intake side.
Air leak, MAF etc.
As is usual with faults like this, if you did something and now there's a problem then chances are it's something you did.
In this case, even after 100 miles I think it could be a wrongly seated intake pipe.
As [ref]colb[/ref] has to keep repeating, if you have an air leak then the DME tries to compensate by richening the mixture. Eventually it can't richen it any more and throws up Cat sensor faults. My guess is it maybe takes about 100 miles to get to that point. :wink:

BTW, I missed your original post and it looks like everyone else did as well, otherwise you would have received this advice before you wasted your money.

That's a great help. Thank you very much.
It does make more sense that it is something related to having bits off for the knock sensor job. I'll try and have a look over everything tomorrow afternoon and see if I've missed putting something back in situ properly.
Car is running fine at present, I assume I am causing no damage if I use it in the morning?

 

[enuff_zed]

I think it would be very odd for all the sensors to fail at once.
I think if it were me I would be looking at some part of the engine system that is common to both banks. Something on the intake side.
Air leak, MAF etc.
As is usual with faults like this, if you did something and now there's a problem then chances are it's something you did.
In this case, even after 100 miles I think it could be a wrongly seated intake pipe.
As [ref]colb[/ref] has to keep repeating, if you have an air leak then the DME tries to compensate by richening the mixture. Eventually it can't richen it any more and throws up Cat sensor faults. My guess is it maybe takes about 100 miles to get to that point. :wink:

BTW, I missed your original post and it looks like everyone else did as well, otherwise you would have received this advice before you wasted your money.

That's a great help. Thank you very much.
It does make more sense that it is something related to having bits off for the knock sensor job. I'll try and have a look over everything tomorrow afternoon and see if I've missed putting something back in situ properly.
Car is running fine at present, I assume I am causing no damage if I use it in the morning?

Bit of extra fuel passing through the exhaust but not much else really; as long as you're not doing hundreds of miles.

 

[Simiewimie]

I think it would be very odd for all the sensors to fail at once.
I think if it were me I would be looking at some part of the engine system that is common to both banks. Something on the intake side.
Air leak, MAF etc.
As is usual with faults like this, if you did something and now there's a problem then chances are it's something you did.
In this case, even after 100 miles I think it could be a wrongly seated intake pipe.
As [ref]colb[/ref] has to keep repeating, if you have an air leak then the DME tries to compensate by richening the mixture. Eventually it can't richen it any more and throws up Cat sensor faults. My guess is it maybe takes about 100 miles to get to that point. :wink:

BTW, I missed your original post and it looks like everyone else did as well, otherwise you would have received this advice before you wasted your money.

That's a great help. Thank you very much.
It does make more sense that it is something related to having bits off for the knock sensor job. I'll try and have a look over everything tomorrow afternoon and see if I've missed putting something back in situ properly.
Car is running fine at present, I assume I am causing no damage if I use it in the morning?

Bit of extra fuel passing through the exhaust but not much else really; as long as you're not doing hundreds of miles.

Great. Thanks again.

 

[Simiewimie]

This sounds very similar, and I had the intake manifold off:

"If you get 4 codes for your O2 sensor heater circuit check your crankcase vent heater under the intake manifold. Mine was rotted so bad that when I touched it with a screwdriver the two wires just fell out. Part is about $90. I spent too much time trying to find a wire fault with the O2 sensor wires - if I had checked this first I would have seen the problem."

Does anybody know if the N52 has a crankcase vent heater around that area?

 

[Barty]

AFAIK, the crankcase ventilation system has heated pipes, the wires of which come together into a junctionbox just at the rear most intake manifold pipe. The PCV for a silvertop engine lives underneath the inlet manifold between the block and the intake.

 

[Simiewimie]

Update

It was the Crankcase Vent Hose Heating Element (amongst other names I've found it called) that was causing the fuse to blow. The same fuse that the O2 sensors share. For the time being I have been able to unplug it (without taking anything apart) and cable tie the wire out the way. I will get a new one ordered and then dismantle the intake manifold again to replace it, when it's a touch warmer and I can feel my hands again.

This particular part seems to have a recall on it in the States but not over here. Ah well, I'm just glad I sourced the problem without unnecessarily throwing too much more money at it... always nice to have a couple of new O2 sensors though.

 

[enuff_zed]

Well we kind of got you there in the end.

 

[Simiewimie]

Well we kind of got you there in the end.

:lol:
Yes. And I am very grateful.

 

[enuff_zed]

Well we kind of got you there in the end.

:lol:
Yes. And I am very grateful.

Tbh, it was you that found the info, but for future reference, always go back to what you last worked on, just in case. And remember it is highly unlikely for lots of things to fail simultaneously, so look for a common link.