Hi!

Interesting problem that maybe someone can help with.

I have an Audi A4 2007 3.0TDI Cabriolet and it has issues starting after a drained battery. It cranks well but doesn't start, it does start with start spray.

What I have done so far that didn't help:

1. Charged battery

2. Checked all fuses (also the ones in the ECU box)

3. New battery (was old anyway)

4. New fuel filter (low on diesel when it stopped working so thought it might help)

5. New fuel pump.

There are no error codes related to the ECU and my consumer ODBII reader can communicate with the ECU. Before the battery was drained it worked fine. And yes, I have tried the various fuel reset "tricks".

What would be the next thing to check?

 

Regards,

Nic

 

 

Hi!

Thanks for your reply.

1. Yes, but did have to pair the key and car (I also did the same on my spare key and added a new battery just in case)

2. Yes.

3. Just the normal ones that are on with the ignition.

4. Yes, and no I did not have to code the radio.

Regards,

Niclas

Hi,

Thanks for the reply!

1. Woudn't there be an error code if the ECU had an issue? Or issue reading error codes in the first place

2. I'll check that tomorrow.

3. Pretty sure the common rail had fuel but will re-check.

4. I changed the feeder pump as it did appear a bit weak. Not done anything to the high pressure one.

5 & 6. Good point, I'll check.

Car is in Neutral.

I have had error codes before, e.g. P1573 "Valve left for engine mounting -N144 interruption" comes and goes probably dodgy sensor. And P3085 "Controlling intake manifold 2 electric for air flow control error". But those haven't seemingly affected abnthing.

Regards,

Niclas

Hi,

Again thanks for the reply.

I haven't yet checked the points you listed but the car was working fine the previous day, so didn't stay unused for long. Battery drained becuade I forgot the lights on.

Regards,

Niclas

Just to update here on what I have done. I got a replacement ECU had a local chap clone my ECU and the car started fine. Cost me a total of 300GBP, so not too bad.

Hi,

1. It did not have any water ingress at all, and no oxidation.

2. Yes, he did.

3. After pairing the key, yes I can.

I'll take a look under the battery, but when I replaced it all looked fine.

Cheers,

Nic