Exhaust gas warning lamp came on while driving

[mkmireku]

Hello, My exhaust gas warning lamp came on yesterday while driving to work. Before it happened it became a little jerky once in a while, but nothing very bad to worry about as it is not very noticeable. The lamp is constantly on but when referring to manual it says it could be a lambda probe fault. I went to halfords yesterday and bought a Wyns injector cleaner to add to the fuel (diesel). I haven't experience any jerk today though but can't say again as it doesn't happen all the time. Has anyone experieced this and what was the fault? Also do you think the injector cleaner might just solve the problem? I am due for an MOT over the weekend. Will this affect whether the car wil pass or not?

[martin1810]

It helps if you say which engine, year etc. I assume you have a petrol engine. I doubt it will pass an MOT with the light on as it usually signifies a fuel/air fault.

[mkmireku]

Sorry, the car is a VW Passat 2.0 tdi, 56reg

[martin1810]

You need a fault code read to see what is strored. It's pointless guessing.

[mkmireku]

Just been to the garage to do scan and it has come out with two faults:
1. Mass air flow P1261
2. Unit injector cyl 1

The mechanic reckons th first one is a false error and being cause by the unit injector cly 1.

He has however reset the system and the exhaust gas warning lamp is off. He has asked to drive it for a while and call him when it comes back again ( as he reckons it will come gack again) and then check again if we get the same faults. Then we can take it from there.

Any thoughts?

[fat controller]

I suggest you take a look at the injector replacement thread (sticky at the top of this forum) and have a read through that if you haven't already done so.

[martin1810]

17669
P1261
PD Unit Injector: Cylinder 1 (N240), Regulation Range Exceeded


This code rarely means anything. If an injector fails, the engine won't run.
I wonder what code you had for Mass air flow. That is more likely to cause the warning light.
Mechanic is right, it is always best to clear the codes and see what comes back.

[mkmireku]

Just been to do my MOT and passed on emissions. So far the exhaust gas lamp hasn't shown for the past three days. Fingers crossed it won't show again. I am begining to think my last fuel fill up last week may have been contaminated and the the Wyns injector cleaner i used three days ago may be doing it's work.

Here is the result for the MOT smoke test

Test
smoke K(1/m)
smoke temp(min/max)

1
4.04
24 24

2
2.79
22 23

3
1.94
22 23

4
1.16
21 22

5
0.61
21 22

6
0.93
21 22

[mkmireku]

Update:
My exhaust lamp came back on again and wnet to the mechanic who diagnosed a fault with injector 1. He has had it replaced but i still have the lamp back on after a few days (23rd to 26th December, 2011). I went to VW for a different problem only to be told that my car is among a range of cars which have injector problems and so i should book it in to be checked and if there is a fault will be replaced for free. Apparently there has just been a recall of some passats. It has just been completed and will be picking it up later to see if the problem is still there. Will upadte some more later on. In the meantime anyone who has a passat my need to check on thiers to save them any trouble.

[auto union]

Worth checking the Turbo intercooler - these commonly spilt on the welded seams and the loss of pressure will cause these symptoms. I assume you have checked/replaced the air mass meter and the EGR Valve?

[mkmireku]

Thanks for your reply. Just collected my car from VW. They changed two injectors for free as part of a recall and have reset the codes, but i am still having the same problem to do with jerk/drag especially in second or third gear. I haven't cheked the EGR valve and air mass meter as it hasn't shown up yet. I will have to drive for a few days until the warning lamp comes on again to do a new diagnosis, hopefully it will show the correct problem.

[auto union]

Definitely have the Turbo Intercooler checked as these symptoms are classic when there is a leak however small

[mkmireku]

Thanks auto union. You were dam right.
After a month of painful hassle with my car the fault has finally been diagnosed and which was all along a cracked intercooler. How on earth that happened is beyond me. I have spent close to a £1000, changing and injector (hopefully will get a refund from VW), then wiring and now the intercooler has been changed just to fix the problems as the latest fault code on the air mas meter never showed up in previous diagnosis until the injectors were changed. I can confirm now that the problem to do with the jerking/juddering is completely gone although at a great expense. The car now drives just like new and i have immediatley seen an improvement in fuel economy by about 3 to 5 miles extra per galon. I am very diasppointed in VW for all the problems that they have caused and seriously considering parting with VW and their family of cars forever as i didn't expect a 5 year old car to pose so much problems. So far almost £2000 has gone down the drain in two weeks short of a year. This is clearly not good economics. i sincerely hope other people who have had my problem will at least have some idea on where to start from to save them the grief i have gone through.