CO reading failed MOT
Discussion
Failed MOT on emissions for CO , Fast idle Max % CO 0.30% reading was 1.24%
2nd fast dile max 0.30% reading was 1.31% so showing more CO when warmer
This Hyundai has only done 38k miles and is a great work car, as its 2001 I need to decide how much cash is worth throwing at it. I stalled it at lights and started a bit hard about a year agop and the enegine warning light came on, then got a scanner and found out it was the O2/lambda sensor reading so changed both sensors with cheapies from fleabay which worked about a week, the sensors are almost £100 each for genuine motor factor ones and may need a CAT too? for that high emissions reading, problem is if i spend that and it is something else underlying like obscure electrical fault its too much for an old car..
shame as its still low miles and runs great
any ideas where to look first or how to isolate the most likely suspect based on readings?
cheers
Take it out for a good thrashing before the test to get it nice and warm. My money is on the cat efficiency being low because it's degraded after many short journeys.
There are other potential causes but the above won't cost you anything, assuming you've got a free retest or even better the garage will check the CO without opening a retest session with VOSA.
There are other potential causes but the above won't cost you anything, assuming you've got a free retest or even better the garage will check the CO without opening a retest session with VOSA.
If your lambda sensors are buggered then it's not surprising it's failing the MoT on emissions. The engine can't work out what fuelling it should be running without the lambda sensor so will be running a safe/default map which will most likely mean it''s running rich, hence high CO.
Replace the pre-cat (upstream) sensor as that's the one that provides the engine with meaningful readings, the post-cat (downstream) one is just there to check the cat is doing what it should. If you've still got issues with high CO then move on from there.
Replace the pre-cat (upstream) sensor as that's the one that provides the engine with meaningful readings, the post-cat (downstream) one is just there to check the cat is doing what it should. If you've still got issues with high CO then move on from there.
The lambda reading being below 1 means the fuel / air mixture is too rich (too much fuel).
The Hydro Carbon readings (unburnt fuel amongst other things) are also quite high, although within limits.
Carbon Monoxide is a by product of incomplete combustion, so again, something wrong on the fuelling side.
Try the pre cat 02 sensor, and resetting the fuel trims, and give the car a good thrashing once it's warmed up.
The Hydro Carbon readings (unburnt fuel amongst other things) are also quite high, although within limits.
Carbon Monoxide is a by product of incomplete combustion, so again, something wrong on the fuelling side.
Try the pre cat 02 sensor, and resetting the fuel trims, and give the car a good thrashing once it's warmed up.
ked sensors for that long.Gassing Station | General Gassing | Top of Page | What's New | My Stuff