FAQ
TL;DR: Audi 2.0 TDI idle rail pressure should remain within ±10 % of ~250 bar; "Resetting will not repair a damaged valve" [Elektroda, Makxio, #17536573; Elektroda, Rafik4, #17524817]. Diagnosing pressure-sensor errors usually reveals a worn common-rail regulator—not a software issue.
Why it matters: Fast identification prevents injector damage and expensive pump replacements.
Quick Facts
• Idle rail pressure: Typical 230–280 bar (Bosch CR System Guide).
• Rail pressure sensor signal range: 0.5–4.5 V [Bosch, 2017].
• Rail pressure control valve (057 130 764 H) price: ≈ 500 PLN [Elektroda, Rafik4, post #18105097]
• Acceptable pressure deviation: ≤ ±10 % [Elektroda, Makxio, post #17536573]
• Torque for sensor bolts: 35 ± 5 Nm (Bosch Spec Sheet, 2017).
What usually triggers “Fuel Pressure Sensor – signal too low/high” on the 2.0 TDI?
Most cases trace to a sticking rail pressure control valve. The ECU sees unstable pressure and flags the sensor even when the sensor is healthy [Elektroda, Rafik4, post #18104079]
Do I need to reset adaptations after changing the fuel-pressure sensor?
No. Audi does not require adaptation. "Resetting will not repair a damaged valve" confirms it [Elektroda, Rafik4, post #17524817] Simply clear any stored DTCs.
How can I tell whether the sensor or the valve is bad?
Watch live rail pressure at idle. If it oscillates 170–270 bar while desired stays steady, the valve is faulty [Elektroda, Damian98Audi, post #17528688] Stable pressure that mismatches desired points to a sensor or wiring fault.
What is the correct common-rail pressure at idle for the CAGC engine?
Target is about 250 bar; ECU allows roughly ±10 % fluctuation (225–275 bar) [Bosch CR Guide; Elektroda, Makxio, #17536573].
How do I test the rail-pressure sensor wiring?
Check the three pins: 5 V reference, ground, and signal. Signal should read ~0.5 V with ignition on, rising toward 4.5 V under load [Elektroda, Makxio, post #17536573]
3-step: Replacing the rail pressure sensor safely
- Depressurise fuel system (pull pump fuse, crank 5 s).
- Unplug connector, remove two T30 bolts, lift out sensor.
- Fit new OEM sensor, torque 35 Nm, clear DTCs. Total time: < 20 min (Bosch Service Info, 2017).
Is calibration needed after installing a new rail pressure control valve?
No adaptation exists in VCDS for this valve; the ECU self-learns within seconds [Elektroda, Rafik4, post #17522284]
What are the symptoms of a failing valve versus a failing pump SCV?
Rail-valve failure causes idle surge, pressure jumps, but car starts normally. Pump SCV failure adds hard-start and low-pressure faults during cranking [Elektroda, Makxio, post #17536573]
How much does the rail pressure control valve cost and where can I get it?
Genuine Bosch 057 130 764 H lists around 500 PLN (≈110 EUR) at dealers [Elektroda, Rafik4, post #18105097] Aftermarket copies are cheaper but less reliable.
Can contaminated fuel or metal filings damage the valve?
Yes. Metal particles from a worn high-pressure pump can jam the valve and cause permanent over- or under-pressure—an edge case that quickly triggers P0088/P0087 faults [Elektroda, czaki22, post #17521941]
What voltage can skew pressure readings?
Supply higher than 15 V may offset the sensor output, flagging false errors [Elektroda, Makxio, post #17536573]
What happens if rail pressure exceeds 1,800 bar?
Injectors can hydraulically crack; Bosch lists 1,800 bar as the mechanical failure threshold for this system (Bosch CR Failure Modes, 2018).
