406oc.co.uk

I have a 2.2i petrol and have an uneven tickover and engine management light on. Last time code was read it said lamda sensor a few times. I replaced that this week and the light cleared and it runs better all round though still a little uneven. The light came on again yesterday.

I serviced it 6 months ago and replaced the spark plugs but today cheaked them and one of them was oily wet and others fine. What can that point to and will that be the cause? I also this week had the throttle body off and checked the stepper motor which is very different to the 2.0ltr one listed in the haynes manual. It all looked clean too.

I will get some Forte injector cleaner to see if it improves but was wondering if it could be a faulty injector rather than dirty? The car has done 86k.

The engine light went off again after start stop the engine several times too today. I would love my own code reader but still cannot find out if any of them will work.

I still have uneven idle but looks like I was right to replace the lamda sensor as I got a reader today and it confirmed 2 codes saying just so. They engine management light did clear itself when the battery was disconnected for an hour but came back on. Now I am not sure if it came on because the fault code was still registered in memory or because there is still a problem with the lamda sensor even though new? Anyhow the code reader cleared the 2 fault codes so I will see if they return in which case I do not know what is causing it.

I still have a slight uneven idle and one plug oiley compared to the rest but have some Forte injector cleaner coming to see if it helps.

I've had similar problems over time with the Peugeot 206.

You could be right about the injector being faulty as they are common faults on some Peugeot engines.

An easy way to check whether you have a faulty injector is to swap the one with the oily plug for another without the oily plug, if the oily plug then moves to where you swapped injectors, there is your problem.
Sometimes on the 206, swapping injectors completely cures the problem.I've done this many times.If you decide to do this, make sure you depressurise the fuel system first or be prepared for a squirt of fuel as you take off the fuel pipe..be careful.

There could also be a couple of other things responsible for the oily plug,
1) There could be a faulty coil pack or individual plug lead/coil, again, swap the possible faulty one for a known good one and see if the fault moves to that plug.
2) It's possible that the cylinder with the oily plug has a valve or piston/piston ring fault, maybe even a tight tappet.A compression check would reveal.

Good luck with it anyway.

I had thought about maybe a piston ring or valve seal too. Thing is I dont remember it doing it before I changed the plugs, maybe i have a faulty one. I would change the plug leads but its all one unit for all 4 plugs, dunno what else is in there or how much it costs. I will take it off at the weekend and see if they are all sparking correctly.

Thing is it runs superb and there seems to be no power loss at all and it dont seem to be smoking either. Just a lumpy idle that makes the car bob about a little lol. Thing is the little things like that bother me when really I should prob not let it as at the end of the day it is 9 yr old with 86k on the clock. Though the 2.2 engine is meant to be a good one. Just not sure it is worth spending too much on it.

Buy a new plug if you haven't got any of the old ones, fit it where the oily one is, also check the end of the 4 pot coil pack for any signs of cracking or splits, tape the end up with insulating tape.
Are they the correct plugs? These engines don't like those 4 prong type.The resistance is different and can cause problems, including putting the management light on.

they are single prong plugs but are different make to the ones which were in originally. The local auto spares supplied them and were the correct length etc. I will check for cracks etc too. Not got the originals now either so may get a different set or see if that one appears to spark weaker etc.

Anyone else got an idea? Today the engine light came on again so I read it and once again the same 2 fault codes which are -

P0136 - Generic - O2 sensor circuit malfunction
P0141 - Generic - O2 sensor heater circuit malfunction

Not is a brand new O2 sensor fitted and I checked the part number on NTK's website to ensure it was right for my car as I got it from ebay brand new boxed.

Could this be the cause of the uneven idle? Is it possible that the electic circuits which control the sensor are faulty or the ecu?

Any help appreciated.

Simon.

Did you know that most cars have 2 sensors?

Pre cat and post cat.

I'm not sure about your 406, but it may have 2.

Perhaps you should have live data checked.

Pretty sure it has one only. Only listed to have one when trying to find the part anyhow and I can see only one too.

I am gonna swap the injectors around tomorrow to see if one is faulty. That way if swapped to a different cylinder and it is the same on that one then it points to the injector, then swap plus to see if it is faulty (They are new but still possible). Then if they are fine it may point to the coil pack which I think aint cheap, then again no parts are cheap for this engine which I wish I would have known before buying, never knew it was so rare . I think it will be main dealer only as not many in the scrappers.

I think if it is missfiring on one cylinder it is triggering an O2 sensor fault due to un burnt fuel being ejected possibly damaging the cat!

Anyone know how to remove the injectors on there engines? When I looked the other day they appeared to be just pushed in and seemed to move when pushed? I dont just want to pull and do damage! My engine is not covered in my current haynes manual and not sure if it is covered in a later one or I may need a 407 book?

Any help appreciated.

jasper5 wrote:Did you know that most cars have 2 sensors?

Pre cat and post cat.

I'm not sure about your 406, but it may have 2.

Perhaps you should have live data checked.

I now feel stupid! I went under again and there is a second one post cat just as you said and my code relates to that sensor. I have changed the front one so looks like I need the rear one too. The connector for the second one is near the first too but hidden under a large loom, doh dont know how I missed it.

I should have bought the code reader before the O2 sensor really. The other thinh was NTK do not list both sensors and only make a replacement for the front one which threw me also. Bosch however list both of them so I will get the bosch one which is just over £80.

Hopefully that will solve the judder!