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[aaronjb]

The CO & HC seem to indicate it's running rich.
The lambda reading indicates it's running lean (15.34:1).

The two don't marry up so I'm going with an air leak into the exhaust in front of the forward O2 sensors confusing the LTFT & STFT.

Possibly, but it could also be that the HC is a little high due to a lean misfire and the CO is pretty much straight-through because the cat isn't working due to the mixture being too lean. Bottom line - it needs a little investigation, but straightforward to find the problem with some thought and maybe a look at the live data.

Good point - it would be interesting to see what the fuel trims are doing and what the MAF output looks like

[steve6367]

I agree with OP that emission tests are an expensive luxury we could do without, possibly desirable in calm California but worth little in draughty England. However, we are stuck with them. On 2 litre Omegas they wre a nightmare; The flexi section would fail after 8 years, I would fit aftermarket cat sections that would pass one MOT and fail the next. I now run 2 2.2 Omegas, both are due MOT in the next three months and I am nervous; both have Timken aftermarket cats fitted. I now avoid 4 cylinder Omegas for this reason.

However your car is a 2.5. I have never known a V6 fail MOT on emissions. What is the mileage? If high it could be dead catalysts. If so, someone on this forum may have a pair kicking around. I probably have somewhere. I have found changing cats got my 2 litre Omegas through MOTs, if only for a year.

I can't agree, local air quality is an issue - although windy sometimes its not always windy and local air quality and so peoples health would suffer. (IMO naturally)

[Kevin Wood]

The CO & HC seem to indicate it's running rich.
The lambda reading indicates it's running lean (15.34:1).

The two don't marry up so I'm going with an air leak into the exhaust in front of the forward O2 sensors confusing the LTFT & STFT.

Possibly, but it could also be that the HC is a little high due to a lean misfire and the CO is pretty much straight-through because the cat isn't working due to the mixture being too lean. Bottom line - it needs a little investigation, but straightforward to find the problem with some thought and maybe a look at the live data.

Good point - it would be interesting to see what the fuel trims are doing and what the MAF output looks like

Yes, exactly.

Something has probably brought the mixture outside the authority of the lambda loop to correct, whether it be MAF output, an intake air leak causing a lean mixture, an exhaust air leak causing the lambda sensor to read incorrectly, etc... Could even be that the engine isn't getting hot enough to go into closed loop (or the ECU thinks it's not hot enough).

The OP needs to get the live data read and to carry out some simple checks before buying any more snake oil.

[Kevin Wood]

I can't agree, local air quality is an issue - although windy sometimes its not always windy and local air quality and so peoples health would suffer. (IMO naturally)

Indeed and, if an emissions check fails, it's almost 100% of the time down to a fault that will be costing the owner of the car dearly in wasted fuel or the potential for other problems, so it's actually a useful thing to do aside from air quality.

The MOT emissions standards really aren't that taxing, after all.

[aaronjb]

Didn't the OP say he was getting 39mpg?  That seems so high it must really be running lean..

[05omegav6]

Didn't the OP say he was getting 39mpg?  That seems so high it must really be running lean..

39kpg more like

I bet the roses in his garden are absolutely stunning...

[ckz]

right.
after second mot retest, i did not get any paper which indicates the fail of the emission.
it was not running on leaded. only suoer unleaded.
i lef the dashcam on also had a camcorder in the back of the car running with front view.

the result
as some people think iam moaning and blaiming someone else.
exlain this to me.

the guy which brought the car from the garage to there own mot place which is 4 miles from the place i was waiting was driving my car on a countrylane 95 miles per hour, for a start.
on the mot place, the failurewas a broken coilspring fron which was inspected by looking from the side only, the handbrake was applied trying to moive the car.
that both was failure before.

to the emission,
you can see on the cams,
the car was running in idle for around 10 minutes while the tester was on his maschines typing around. he never was behind the vehicle in this time.

how could the sonde be applied.
he opened the bonnet looked into the engibay shaked hios head and that was it.
car was brought back to me and i been told failed emission on same levels.

but they prepared to sort me out leaving it with them and he get a mechanic on it.

today MY mechanic called him regarding this camcorder evidence and he was very quiet and did hardly say nothing about.
he actually said if i would cime back he would sort me proper out.

yesterday when he said his mechanics wuld take care of thos proble i asked how muc and he said about 3 to 4 hours labour plus whatever needs to be exchanged or new to pass.

sorry but im not stpuid and feed him because he thinks iam a mug.
i just send him an email demanding my money back or i bring this official into the news which is a small community he lives in.
i dont really care if he needs customer to survive or not, thats not my problem. and i defently do not pay his wages or that fro is mechanics.

now the car is booked in to another garage without workshop. after i explained why the guy said look like he want to make a fast one with you.

so tell me about that then. instead having a go at me because iam not prepared paying out a lot to this guy for mot.
there is always a decition and a question this to it.
braindead acceptance means spending money and make others happy. dos it ?

[Kevin Wood]

Sounds like the previous guy was guessing, so you're doing the right thing to demand your money back.

4 hours labour to diagnose an emissions fail?  Hopefully the next guy will be better.