Tech Tip: Volkswagen’s MIL On with DTC P129F/P310B Set – UnderhoodService

Tech Tip: Volkswagen’s MIL On with DTC P129F/P310B Set

Due to fuel intrusion into the low pressure side fuel pressure sensor (G410), a false signal may be sent to the ECM resulting in a reading that is out of tolerance. A false signal may result in illumination of the malfunction indicator lamp (MIL) and DTC P129F or P310B being stored in fault memory. There is now an improved fuel pressure sensor (G410) to aid against fuel intrusion.

 

Models        Year          Eng Code    VIN Range
(A5) Jetta    2006-’08  2.0L (BPY)    1K_6M000001 to 1K_8M006349

Eos              2006-’08  2.0L (BPY)    1F_6V000001 to 1F_8V003115

Passat/        2006-’08  2.0L (BPY)    3C_6E000001 to 3C_8E008949
Passat Wagon            
                                    3.6L (BLV)    3C_6P000001 to 3C_8P007918

GTI              2006-’08  2.0L (BPY)    1K_6W000001 to 1K_8W001130

Touareg/      2007-’08  3.6L (BHK)    All
Touareg 2

 

Condition: MIL on, DTC P129F and/or P310B stored in ECM fault memory.

Due to fuel intrusion into the low pressure side fuel pressure sensor (G410), a false signal may be sent to the ECM resulting in a reading that is out of tolerance. A false signal may result in illumination of the malfunction indicator lamp (MIL) and DTC P129F or P310B being stored in fault memory.

There is now an improved fuel pressure sensor (G410) to aid against fuel intrusion.

Service:

Note: Do not replace the fuel system components for the DTCs listed above before completing this technical bulletin.

For 2.0L (BPY) and 3.6L (BLV, BHK) FSI engines:

1. Check to ensure:

– DTC P129F and/or P310B are stored in DTC memory.

– No other fuel delivery system DTCs that clearly indicate a component failure (DTCs for fuel delivery system component electrical faults) are present.

2. Start the engine and allow it to idle.

3. Disconnect the fuel metering valve connector (N276) on the high-pressure fuel pump.

4. Compare the fuel pressure values from MVB (Measuring Value Block) 103 field 1 and MVB 106 field 1.

5. If the MVB 103 value deviates more than i 0.5 bar (7.25 psi) from the MVB 106 measurement, then the DTC was likely triggered by a faulty low side fuel pressure sensor. In this case, replace the low-side fuel pressure sensor.

a. Clear the DTCs and verify that the concern is resolved.

b. Run Basic Settings 103 to adapt the system.

c. If the problem persists, further fuel system diagnosis is required.

Tip: Some technicians may still wish to use a mechanical gauge to check fuel pressure.

To verify low side fuel pressure, a mechanical fuel pressure gauge may be connected in the engine compartment.

– Add 1 bar (14.5 psi) to the value obtained from the mechanical gauge to calculate the adjusted gauge measurement.

– Compare the adjusted gauge measurement to the value stored in MVB 103 field 1.

– VAG 1318 gauge installed on a 2.0T FSI vehicle.

Tip: MVB 103 field 1 value should be approximately 1 bar (14.5 psi) above the mechanical gauge reading. This is a normal condition and does not indicate a faulty sensor.

Courtesy of Identifix.

 

 

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