AHF Starting Problems: Troubleshooting Guide

Hello there.

I'm having starting problems with my A3 AHF (81 kW). (I've read the relevant posts in the forum and have largely checked the things mentioned.)

The machine has 120,000 km on the odometer and has been experiencing starting problems recently, specifically when the temperature is between 10 and 15 degrees Celsius (it takes 7-8 seconds of cranking before it initially sputters, then starts, and then produces a white cloud of smoke). The glow plugs, glow relay, and engine temperature sensor are all working correctly.

When the ignition is turned ON and when starting the engine, I have a control voltage of 7V at the glow plug relay. This is obviously not enough to trigger the relay. After the engine starts, the afterglow function works perfectly for about 30 seconds.

After extended periods of inactivity, I've observed some air bubbles in the diesel lines, but not in large quantities. The lines connected to the diesel filter don't appear to be leaking.

Otherwise, the machine is working perfectly. The performance and power are all good. There are no errors in the memory.

What should I do ????

hello,
I have the same unit. Please check if relay 109 is working properly.
There might be a solder joint on the relay that is about to fail. In my case, that's what happened.
The behavior is similar...

Hi there,

'I'll need to investigate that again. I think I might have noticed something when it first started. It's clicking, which doesn't necessarily mean anything, but you're right. I'll check if there's any continuity, or ideally, just replace it.'

Greetings

It's enough if you just re-solder all the solder joints.
My old relay had an air gap of 1.5mm at a solder joint!
The car barely moved with it installed.
I replaced it, and since then everything has been fine...

@Wieseldiesel: Did you find the problem? If so, what was it?