Intermittent Amber Check Engine Light

[bluerallye]

Quick search but no joy.

'93 2.5 AAF Auto

Had an intermittent amber 'check engine' light (part of the 3-light (Brake/Engine/ABS) warning cluster next to the heater controls) at the weekend after prolonged section on motorway (3 hrs).

Seemed to be co-incident with engine being under moderate load (such as a moderate incline) and only occurred in lock-up (4th). Crawling through the mountains in 2nd / 3rd under similar or higher loading didn't bring the light on but i wonder if this is because the engine 'had somewhere to go' w.r.t revs / torque converter due to the 'box not being in lock-up.


Once lit, a roll-off the throttle would immediately extinguish the light and it would stay off until the next time.

No notable impact on fuel consumption, no notable loss of engine performance, no other signs apparent. Happened regardless of having cruise-control set.

Anyone had anything similar?

It's going into my local specialist for VAGCOM interrogation this week to see if there is anything logged in the memory so will update on here for future reference.

 

[Robinjd]

Hello, I have a 94 Westfalia, same thing happened on my vehicle. Checked the OBD and it was the oxygen sensor, simple fix.

 

[bluerallye]

Thanks. Volkservice couldn’t find a diagnostic port. I have a new O2 sensor somewhere so I’ll change it on spec

 

[Robinjd]

my vehicle is a 94 and the diagnostic is above the fuse panel. will send pic if interested.

 

[bluerallye]

Yes please whenever you get a minute, no rush. Cheers!

 

[Robinjd]

the connections for diagnostic in a '94 westfalia are the black and white connections at the top of the picture.

 

[bluerallye]

Thanks very much, appreciated.

 

[bluerallye]

Update just for anybody that has similar in the future.

No diagnostics logged.

Pulled out the coilpack - Still on original VAG / Telefunken part (stamped Aug '93) and looked very corroded, also the orientation of these don't help as they are susceptible to water ingress. Changed on spec and with a new set of plug leads. No more intermittent amber check engine light observed after a few motorway runs.

Also noted lo-speed fuse had gone and hi-speed was looking old too. 2 x new 50A fuses fitted and both fans now running as intended. Happy van....

 

[bluerallye]

Old thread and I no longer have the van but the potential ‘cure’ is logged here for future reference.

Seems the problem deteriorated into hunting at idle and brought running. Cured by a new set of vacuum lines. Seems legit as the cruise was vacuum controlled.