B7 A4 2.0T is p

**Dondbg** · 03-20-2025 06:50 PM

Need your opinion on this.

I have an A4 B7 2.0T Tiptronic, and occasionally, I get multiple fault codes.

I suspected a voltage issue, so I installed a fresh, correct-spec battery and noticed the battery fuse was an aftermarket one—so I replaced that as well. While inspecting further, I found that the ECU had been replaced, with a much newer date stamp compared to the car’s 2007 model year. This suggests that at some point, there was a major electrical issue, possibly a short to ground that fried several components.

The problem only occurs during startup. Since the battery is healthy and the alternator is charging properly, I’m now leaning towards a faulty starter relay or solenoid. It may have been damaged as well, causing a voltage drop. Worth mentioning—when cranking, the starter feels slower compared to my other A4.

Recently, an O2 sensor code appeared, which is new and makes me think the issue is getting worse. The strange part is that this only happens during cranking. Most of the time, the car starts immediately and runs perfectly. But when the issue occurs, it starts rough, almost like it’s not getting fuel, then picks up and settles while throwing multiple codes.

Address 01: Engine Labels:
Control Module Part Number: 8E0 910 115 Q HW: 8E0 907 115 D
Component and/or Version: 2.0l R4/4V TFSI 0030
Software Coding: 01040003190F0020
Work Shop Code: WSC 39197 001 104857
VCID: 2F7933DB271DB97AB6BADD1-807A
9 Faults Found:

001602 - Sensor Reference Voltage A: Circuit
P0642 - 002 - Low - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: -40.0°C
Temperature: -40.0°C
Absolute Pres.: 0.0 mbar
Voltage: 0.000 V

001112 - Evap System Purge Control Valve (N80)
P0458 - 002 - Short to Ground - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 171 /min
Load: 70.2 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 11.049 V

000052 - Turbocharger Bypass Valve Control Circuit
P0034 - 002 - Low - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 171 /min
Load: 70.2 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 11.303 V

000581 - Solenoid Valve for Boost Pressure Control (N75)
P0245 - 002 - Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 171 /min
Load: 70.2 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 11.303 V

005490 - Left Engine Mount Solenoid Valve (N144)
P1572 - 002 - Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 171 /min
Load: 70.2 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 11.303 V

008853 - Fuel Pressure Regulator Valve (N276)
P2295 - 002 - Short to Ground - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100010
Fault Priority: 0
Fault Frequency: 4
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 50.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 11.938 V

000048 - Oxygen (Lambda) Sensor B1 S1: Heating Circuit
P0030 - 004 - Malfunction / Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 1236 /min
Load: 14.5 %
Speed: 28.0 km/h
Temperature: 67.0°C
Temperature: 35.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.970 V

000054 - Oxygen (Lambda) Sensor B1 S2: Heating Circuit
P0036 - 004 - Malfunction / Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90525 km
Time Indication: 0

Freeze Frame:
RPM: 774 /min
Load: 32.5 %
Speed: 0.0 km/h
Temperature: 75.0°C
Temperature: 37.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.716 V

012555 - Low Pressure Fuel regulation
P310B - 004 - Fuel Pressure Outside Specification
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 90537 km
Time Indication: 0

Freeze Frame:
RPM: 1942 /min
Load: 48.2 %
Speed: 64.0 km/h
Temperature: 93.0°C
Temperature: 27.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.843 V

Readiness: 0000 0000

**Cyrik** · 03-20-2025 10:38 PM

Yikes. You have either a relay/fuse problem, wiring harness problem, or an ECU problem.

First one is basically free to diagnose and check, same with the second, third is not.

I'd start diagnosing in that order if it were my car.
If you clear codes while it's running, does anything come back immediately? Check starter wire (Positive) and all ground connections as well.

**Jayz691** · 03-21-2025 09:27 AM

You can see them coming back in the order that they are posted here. The first one or two trigger at 0 RPM, 0 load %, etc. The next few are all triggered at 171 RPM 70% load, which I'm guessing is while it's trying to start and turning over. And then the last one or two are triggered at 1200 RPM, I'm guessing as soon as it starts and high idling, and O2 sensor is heating up.
A lot of those sensors and solenoids are on the same harness and often trigger when you get water in the ECU. I'd be looking at the relays and fuses in the ECU box first.
I'd read up on that first initial code first, that may be causing all the other ones to pop too. That's just kind of a guess going off of those freeze frames on your scan.

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