AHF Failure: Troubleshooting & Solutions

Hi everyone,

I drive a Golf AHF with 92,000 km (approximately 57,000 miles). Today, it happened twice that the car simply stalled while driving. In both cases, the preheating light was on and the oil warning light was flashing. However, the oil level and coolant level were within the specified range each time. When I tried to start the car, it wouldn't crank because it wasn't preheating at all. Even prolonged cranking didn't help. After about 5 minutes, I tried starting it again, and lo and behold, it started preheating again and immediately started up.
8 hours later, the car had cooled down completely again. While driving, it lost power or stalled briefly. However, this time, the preheating light only illuminated for a fraction of a second, and the car restarted on its own without me having to use the starter motor again.

Could the problem be due to insufficient power supply to the control unit? I think it might be related to relay 109... Tomorrow, I'm going to VW and hoping there will be some useful information in the error memory.

But maybe you could give me a few tips so I can pass them on to the guys at VW!

Best regards, Chris.

Hello,

If it was indeed relay 109 that caused the problem, then the error memory will only contain a lot of irrelevant information => which is the best indication of that!

Hi,

I also experienced the problem where my vehicle turned off while driving and then the glow plug light came on.
The cause of the error was a faulty immobilizer control unit.
Since the control unit was replaced, everything is working again.

Boss.

... after my car wouldn't start at all yesterday, it was towed away and the voltage supply relay 109 for the control unit was replaced. Since then, everything is working again. Fingers crossed .

Best regards, Chris.