Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: omegarvey on 09 May 2008, 09:49:53

Title: MOT Failure on emissions. Cat or Lambda?
Post by: omegarvey on 09 May 2008, 09:49:53

Hello.

Just had car MOT'd and it failed spectacularly on emissions. Here are some of the results at fast idle.

CO %vol 5.979 (should be about 0.3)
HC ppm vol 283 (should be about 200)
Lambda 0.841 (should be 0.97 - 1.03)

The Engine Management Light had been on, and I believe the code points to the LAMBDA sensor. Could the sensor make these high emission figures, or is it likely that the cat has failed and is causing the sensor to flag a fault.

Any advice greatly appretiated.

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: jonathanh on 09 May 2008, 09:52:39

get the code read - do a 'paperclip test' and post thefault codes up.  They'll give us a better clue

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: Entwood on 09 May 2008, 10:12:25

Faulty LAMBDA can lead to overfuelling and high emissions .. BUT long term overfueling - especially unburned fuel - will lead to CAT failures .. so could easily be a bit of both ... the CAT bit being the expensive bit !!

Paperclip test here :

http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

run that and post up the results .. :)

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: omegarvey on 09 May 2008, 10:19:03

Already did the paperclip test. Only one code, 0130.

I believe it points to the following on an X20XEV...

P0130 O2 Sensor Circuit Voltage High C-28
P0130 O2 Sensor Circuit Voltage Low C-28
P0130 O2 Sensor Range/Performance C-28

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: Kevin Wood on 09 May 2008, 11:31:47

That is running extremely rich, so it's more than just the cat. Normal CO level without or with a failed cat would be under 2%.

Is the temperature gauge at approximately the mid point during normal driving? Also, check the coolant temperature sensor, as it's possible that the ECU is not seeing true engine temperature and is staying in warmup enrichment.

Other than that the Lambda sensor is a possibility, I guess. :-/

Kevin

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: omegarvey on 09 May 2008, 11:41:16

Yep, temperature always around mid point. Sometimes a little higher, and sometimes lower.

Would the coolant temperature sensor not be showing an engine management fault then?

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: Matchless on 09 May 2008, 12:15:48

ECU is sure there is something wrong with the lambda sensor.
Check the connector to the Lambda and follow the cable back to make sure it hasnt melted on the exhaust or got trapped somewhere.

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: Kevin Wood on 09 May 2008, 12:59:19

Quote

Yep, temperature always around mid point. Sometimes a little higher, and sometimes lower.

Would the coolant temperature sensor not be showing an engine management fault then?

If completely disconnected it would, but if mis-reading the ECU has no way of knowing it's not the correct temperature.

Kevin

Title: Re: MOT Failure on emissions. Cat or Lambda?
Post by: omegarvey on 09 May 2008, 13:08:10

I am pretty sure the LAMBDA is not damaged, melted or trapped. I have "had it off" a couple of weeks back.

Here is one of my related posts.

http://www.omegaowners.com/forum/YaBB.pl?num=1209392786/0#0