I recently bought an Audi A4 with the 1.8T. Has had a cranking no start since I purchased it. I was told that it broke a serpentine belt cause the AC locked up. The previous own had the AC removed and a new belt installed however a P0011 was thrown and then cleared.

Since I purchased I have:

- Replaced Cam Sensor
- Replaced Crank Sensor
- Replaced both ECM Relays
- Cleaned Battery Terminals
- Cleaned ALL Grounds
- Replaced all plugs
- Checked ALL fuses
- Checked Compression
- Checked Timing
- Checked Fuel pressure
- Disconnected battery for 5 minutes
- Unplugged and replugged in every sensor.
- Pulled codes (Recently got P0685)
- Replaced ECU (From an automatic)

I have fuel just no spark I have checked the harness all the way back to the ECU it looked good. The no spark issue is what prompted me to change crank and cam sensor. I did noticed that when cranking there is no output by the MAF sensor however the MAP sensor is working.

I've officially ran out of ideas.

 

Fuse 29 has 1 volt......

 

Sounds like the ECU is not getting power like it should. 1volt? That's about 11 short.. Check any relays that relate to the ECU. I don't have a diagram to look at but most are labeled on the relay panel covers. There are at least 2 relay panels in these cars today. I'd suspect that the relay panel with the one for the ECU is in the forward footwell on the passenger side behind the carpet that runs up the firewall area. P0685 indicates an ECU power issue: https://www.autocodes.com/p0685_audi.html