G'day everyone.

I have a nice Marea Weekend 1.6 petrol. Good motor, plenty room...but it failed its MOT the other day. I have repaired all the defects, wishbones, rods, fuel breather tank in the wheelarch, but the emissions are over. I think I need to replace the Lambda sensor, but i'm not entirely sure where to find it!
I have found a sensor on the right side of the head, but as there was water seeping out when i undid it slightly this made me think i was on the wrong one. Was it the Lambda after all?

Anyone help?

Rascal808

Hi mate,

Its on the exhaust. looks a bit like a spark plug. It basically varies resistance with the amount of unburnt oxygen in the exhaust. This in turn tells the ECU if the car is running lean/rich and as a result makes adjustments to the fuelling to sort it.

Hope that helps,
Alan

Hello again.

Thanks for the info, located the sensor, 4 wire rectangle type plug.

BUT...... my local Dingbro motor factors has just informed me there is another sensor towards the rear of the exhaust

I had a new exhaust system from the cat back fitted last month. Did not see anything that resembled a place for another lambda...

Where would it be fitted? I'll go climb under again and have a look...

Thanking you already...

Rascal808

Hi mate

Yes if yours is the later model, you will have a pre and post cat lambda. The pre one is on the exhaust manifold, and the post one is just below the cat, which is the big bit just after the manifold. If you have the CF2 version, then there is only 1 lambda sensor. This is located on the downpipe just after it turns 90degrees and goes under the engine, where the 2 pipes turn into 1.

Hope that helps,
Alan

Ello again.

Well been under the car and cant find any evidence of another lambda. I think i have the CF2 version judging by the position of the Lambda that is there..



Can you tell from the photo?

Rascal808

Yep that's the bad boy. Soak it with WD40 or penetrating fluid and leave it for a good half hour or some before you try and remove it if your going to do it yourself. As you can see, they seize in fairly well sometimes. If its still hard to get out, you can heat the exhaust around the lug with a blow torch or similar to help release it.

Good luck,
Alan

Thank you sooo much Alan, car forums are great for DIY car repairs.

Can I ask, after i have fitted the new Lambda, will I have to disconnect the battery for a few hours to allow the computer to reset to the new Lambda.

And if I do, where do I obtain the code for the radio when I reconnect the battery?

Questions questions I know.....

Speak again soon no doubt....

Rascal808

Lol, no problem, thats what its here for!

You dont necessarily need to re-set the ECU as it will learn fairly quickly with the new lambda, especially if you take it for a good run before you get the emissions re-tested. If you do, leave it of for an hour or so. Normally, depending on the type of radio you have, you will not need the code, as the head unit will be recognised by the cars CAN network. If n ot, they can easily be obtained from fiat, or I may be able to help you if you supply me model number, serial number etc.

Alan

Well, we shall see if the emissions are OK this afternoon. Fitted the new Lambda, a new Air filter, a new set of spark plugs.
The car does seem to sound sweeter, but they always do to me when I've done a little service on them. I've left it idling for a half an hour now, I think I'll go take it for a quick run so the ECU can 'learn' the new sensor readings and adjust what it needs to.

rascal808

Good luck,

let us know how you get on!

Fingers crossed,
Alan

Well.
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It Failed the emissions again.

Fast Idle Test Min Limit Max Limit Actual Value
RPM 2450 2950 2829 PASS
CO ---- 0.300 1.953 FAIL
HC ---- 200 119 PASS
LAMBDA 0.970 1.030 1.033 FAIL

Natural Idle Test
RPM 700 950 802 PASS
CO ---- 0.350 1.518 FAIL

FAILED


Got it plugged in to a Diagnostic/Engine management reader machine on the way home and everything seems to be working fine. Nothing that would point to causing this problem, only one minor fault code thats unrelated, and now reset.

That would leave me thinking that it MUST be the CAT.

Waddya think? I would appreciate any tips, suggestions folks...

Rascal808

rascal808 said:

That would leave me thinking that it MUST be the CAT.

Click to expand...

high CO + high lambda + normal HC = cat or downpipe leak or lambda.

jug said:

high CO + high lambda + normal HC = cat or downpipe leak or lambda.

Click to expand...

Nice one jug. My new cat will be here in the morning, just took the old one off - it looks a bit ropey so hopefully all will be well emission wise after fitting the new one. Had a quick look for any leaks, nothing I can see so fingers crossed.
For info - buying online is £50 ish, motor factors quoted £230

Rascal808

And once again,
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IT PASSED IT'S MOT !!!



No problems with the emissions with the new CAT fitted, all is well. This has proved to be a more expensive MOT than I expected. Never mind though - once it's done it's done. Hopefully be a fly thru next year...

Rascal808

rascal808 said:

And once again,
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Click to expand...

you fooled me there