Emissions

[Shaprog2010]

Hi, I have a Peugeot partner horizon 2008 and it failed the MOT on emissions, I removed the top of the air filter box and when I opened the butterfly flap on the throttle body it was black and oily inside, is this normal. The pipes that go to the charcoal canister have black oil in too. I removed the spark plugs and they are in good condition and are the right colour.

[PaulC5]

It is usual to clean inside the throttle body at servicing, at least I do, by spraying with carb cleaner or wiping with a cloth damp with turps/white spirit. Once you have done this then you can get an idea of how quickly it returns.

It could be your catalyst is due for replacing, how many miles has it done ? Do you have the engine management light on, any fault codes when you plug it in to a code reader ?

[ozvtr]

How long have you had the car? Is this the first MOT you have done with the car?
Does the engine light come on when you turn the key to ignition but do not start the car?

An emissions fail should bring on the engine light. If the engine light comes on and then goes out when you start the car, but fails the emissions test, I'd say your engine is consuming too much oil.
An overly rich air/fuel mixture will fail MOT but only if the catalytic converter is failing. But that should bring on the engine light.

Again, it's important that the engine light comes on when you start the car and then goes out when the engine is running. If the engine light NEVER comes on, then the person who sold you the car has been naughty (to say the least!).

[RichardW]

Need to see the fail sheet to see what it failed really.

[Shaprog2010]

I've only had the car for 6 months, apparently it failed the last 2 MOTs on emissions and then mysteriously past. MOT fails are exhaust carbon monoxide content exceeds limits and exhaust lambda reading after 2nd idle outside limits. The eml is on and fault code is P0134. Garage says it could be catalytic converter or quite a few other things. Car has done 84000 miles

[RichardW]

P0134 is upstream oxygen sensor, so that appears to be the place to start.

[ozvtr]

I've only had the car for 6 months, apparently it failed the last 2 MOTs on emissions and then mysteriously past. MOT fails are exhaust carbon monoxide content exceeds limits and exhaust lambda reading after 2nd idle outside limits. The eml is on and fault code is P0134. Garage says it could be catalytic converter or quite a few other things. Car has done 84000 miles

It would have been nice if you had told us this in the first place.

High carbon monoxide is high air/fuel ratio. That combined with the P0134 points to the upstream O2 sensor (as RichardW says). It could also point to a wiring problem between the O2 sensor and the engine ECU. HOWEVER "exhaust lambda reading after 2nd idle outside limits" points to an aging catalytic converter. BUT there is no P0420 CAT code? MOT picked it up but the engine ECU didn't? That's strange.
As RichardW says, I would change the upstream O2 sensor. But the P0134 will probably need to be cleared by a scanner.

[RichardW]

If it's running rich because the O2 sensor is telling lies there won't be enough oxygen to burn the CO in the car hence high CO and lambda out of whack.

Get the sensor working (could be wiring) then see if it will go into closed loop and hope the cat is still OK.

[Shaprog2010]

Hi, just a quick update, I removed the old catalytic converter and it was completely hollow, it may have been blocked and that's why they removed the center but it was still going to fail the mot. Hopefully the EML won't come on now.

[ozvtr]

Hi, just a quick update, I removed the old catalytic converter and it was completely hollow, it may have been blocked and that's why they removed the center but it was still going to fail the mot. Hopefully the EML won't come on now.

I am still concerned about the lack of a P0420 aging CAT code.
Was there an extra sleeve (extender) attached to the downstream O2 sensor?

[Paul-R]

Have you replaced the faulty cat with a new one or what?

[Shaprog2010]

Yes I've replaced the cat and there is no extra sleeve for the O2 sensor

[Shaprog2010]

I booked my car back in for mot and it failed on same emissions, garage says it could be because of new cat not good enough. I've phoned Peugeot and they say they don't supply a cat for my car anymore, does anyone know where I can get a good quality catalytic converter for this rubbish car

[PaulC5]

If you still have P0134 fault code then you need to do something with the upstream lambda sensor. If your code reader does live data see what values it is giving and then decide if it is working or not.

[Shaprog2010]

I'm going to test the lambda sensors with a multimeter. There is a sensor in the manifold and another in the exhaust just after the catalytic converter, can anyone tell me how to test them and what readings they should give please