Passat B6 170CR Limp Mode - 'Engine Fault. Workshop!' warning LED

olewy

Car: late 09 Passat B6 170 CR DPF
Issue: Warning LED & notification; "Engine Fault. Workshop!"

Symptoms:
1. Reduced power & acceleration (as if turbo not kicking in).
2. Turn car off & back on; warning LED & notification is gone, limp mode gone (power restored).
3. Issue occurred 2 times so far. First time was yesterday in traffic while moving (slightly stop start traffic but mainly moving constantly) & once again today shortly after restarting the engine after a motorway drive.
4. Car has been slightly slower to turn over from cold of late.

Suspecting either battery, alternator, EGR valve or DPF (hopefully not) but I've no clue.
The car does get good daily runs on a motorway with a heavy right foot so would be surprised if its the EGR, although more heavy stop/start traffic of late.

Battery age; unknown. Bought the car from a UK dealer 2-ish months ago. No other issues. Comprehensive AA inspection at the time gave it the all clear. Fluids changed in service just before purchase.

I'd prefer not to have to pay for diagnostics, parts replacements etc if it can be avoided.
Thinking of taking the car for a good 1 or 2hour drive/blow out to clear the EGR valve & charge the battery fully, based on what I've read before re diesels, & see how it is then.

Anyone else come across this issue/symptoms or have recommendations for troubleshooting/resolving it with as least expense/time as possible?

tossy

If you are anywhere near or in Kildare i can scan it for you to see what fault codes are stored.

olewy

Does anyone here know of anybody in the north Wicklow or South Dublin area with a VAG decoder & VAG engine experience to see what code(s) is/are present?

dieselbug

I would say the cost of a two hour hard drive would go a long way towards paying for a proper diagnosis.

olewy

dieselbug wrote: »

I would say the cost of a two hour hard drive would go a long way towards paying for a proper diagnosis.

Agree.
Revved it up to 3krpm from 1st to 4th for short bursts, the issue didn't return.
Hooked it up to a friend's VCDS. Output;

1 Fault Found:
001027 - EGR Valve (N18): Malfunction
P0403 - 000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 2
Fault Frequency: 2

Freeze Frame:
RPM: 1288 /min
Speed: 56.0 km/h
Load: 90.6 %
Load: 100.0 %
Lambda: 98.6 %
Mass Air / Rev.: 620.0 mg/str
Temperature: 55.8°C

Cleared the fault code, hasn't returned since.
Briefly reading re '001027 - EGR Valve (N18): Malfunction' on a VAG forum implied potential clogging up of the EGR (may require cleaning). We'll see.

If anyone here has a DIY guide to cleaning the EGR on the 170 CR that'd be great.

Waterson

Im not sure the original issue is being addressed. The freeze frame data suggests the fault was flagged at speed, not in traffic or when just strating of as you experienced it and mentioned in your original post. While a clogged EGR valve would cause a limp home mode, the valve doesnt get actuated until crusing speeds anyway, so would have no effect at idle. Do have the EGR vakve cleaned ut and then actuated using VCDS to confirm operation, but be wary this could be a red herring...