Phase 1 172 MOT failed, advice please

[chris79]

MOT failed on ABS warning light (on the dash says ABS and SERV)...

Also on emissions, apparently too high on all tests.. guy in the garage couldn't plug into the computer as it was unavailable.. reckons maybe the CAT?

CO level = 5.91% (max allowed 0.2)
HC level = 328ppm (max allowed 200)
Lambda = 0.84 (min 0.97, max 1.03)


Any ideas roughly, are these common things or easy to fix?

​Cheers.

 

[lemonnobby]

Lambda reading aint right i would try that first

 

[chris79]

£55 from Eurocarparts.. is it an easy job.. just plug connector and spanner it into the exhaust manifold?

 

[Daniel]

And smash your knuckles to bits getting the old one out, yeah.

 

[chris79]

Ok from what I've been reading, lambda sensors last between 30-50k miles and a low reading would cause the engine to run rich putting CO and HC levels through the roof (which appears to be the case here for me)...

Wonder if it's worth splashing £55 on a new sensor then and asking the garage to retest it... I've never changed a lambda sensor before, is it a bonnet job or under the car job?.. can anyone give me a brief overview of what's involved to change it?

​Thanks!

 

[ben lee]

look more like the engine was not up to temp than a faulty o2 sensor.
did you get a print out of the emissions? did they do two fast idle test then an idle test?
or did they just do a BET test?

​did it fail the idle test too?

 

[Dan@SJM]

Lambda sensor is my bet.

 

[chris79]

look more like the engine was not up to temp than a faulty o2 sensor.
did you get a print out of the emissions? did they do two fast idle test then an idle test?
or did they just do a BET test?

​did it fail the idle test too?

Fast idle test #1
CO 5.91%
HC 328ppm
Lambda 0.84
FAIL

Fast idle test #2
CO 5.83%
HC 297ppm
Lambda 0.84
FAIL

Normal idle test
CO 0.17%
PASS


Guy at the garage said he'd got the engine up to running temp etc.. I reckon it's probably the lambda sensor too..

 

[ScottyRS]

My CO was 8.2% so much more than yours. I changed the two lambda sensors, spark plugs and an oil change and then took it on a good drive down the motorway... job done.

 

[chris79]

Cheers guys - to update on this, I bought a new pre-cat lambda sensor from Eurocarparts (Bosch, £55)... had it fitted by my local garage and bingo, emissions completely sorted!