P0192 means the engine control module saw the fuel rail pressure sensor A signal below its minimum acceptable voltage. Volkswagen's specification puts the threshold at signal voltage below 0.2 V. The family is P0190 (circuit), P0191 (range or performance), P0192 (low), P0193 (high) and P0194 (intermittent). A three-wire sensor with a 5-volt reference sits near 0.5 V at zero pressure; below the floor means the signal is being pulled to ground, the reference is gone, or the sensor's element has failed.
Severity: moderate to high. Can you keep driving? Not far. The module cannot manage rail pressure without a trustworthy reading, and most calibrations fall back to reduced power or refuse to start. On a diesel the module protects the injectors by cutting fueling.
The gauge-versus-sensor test
Audi's bulletin 2027306/4 (October 2014) for the 2008 to 2012 A3, A4, A5, Q5 and TT with the 2.0 T covers P0087, P0088, P0192 and P119A with a single test: compare a mechanical gauge on the rail with the sensor's reading on the diagnostic tool. If the difference is greater than 500 kPa, test the wiring to the sensor; if the difference is still greater after the wiring test, replace the sensor. If the difference is small, the sensor is telling the truth and the problem is pressure.
That test is the whole diagnosis for this code. It separates a sensor lying about pressure from a rail that genuinely has none.
The Mazda cases
- Mazda3, Mazda6 and CX-5 with the Skyactiv 2.0 L and 2.5 L (bulletin 01-010/14, April 2014): P0191 on most models and P0192 on the 2014 Mazda3, caused by the high-pressure fuel pump not generating target pressure due to a manufacturing error in its internal parts. The repair replaces the pump with a modified one, plus the pipe and seal. The sensor was correct; the pressure was not there.
- CX-9 2016 to 2018 built before November 2017 (bulletin 01-003/18, February 2018): a lack of power with no codes, caused by the module limiting power when the low-pressure pump's learning value exceeded a limit. Mazda changed the logic so the engine is no longer limited, and noted that after the change P0192 or P0087 is stored instead when fuel injection is insufficient. On those vehicles P0192 became the way a weak low-pressure pump announces itself.
Causes, in the order they are found
A signal wire shorted to ground by a chafe in the engine harness.
A lost 5-volt reference, often shared with other sensors that set codes at the same time.
A connector with fuel or moisture bridging the signal to ground.
A failed sensor, confirmed by the gauge comparison.
No pressure in the rail: a high-pressure pump not delivering (Mazda's Skyactiv case), or a low-pressure pump too weak (the CX-9 case), with the sensor reading truthfully low.
The module, last.
A diagnostic order
- Record companion codes. Other sensors on the same reference setting codes means the reference; P0087 beside it means check pressure as well as circuit.
- Key on, engine off: read the sensor. It should sit at the zero-pressure value, about 0.5 V. Near zero means the circuit or the sensor.
- Unplug the sensor, key on: about 5 V on the reference, under 0.1 V of drop on the ground, and the signal at the module's pull-up. Signal at zero unplugged means the wire is grounded.
- Put a gauge on the rail where the manufacturer provides a port and run Audi's comparison: a difference over about 500 kPa is a sensor or wiring fault; agreement means the pressure is really low.
- If pressure is really low, follow the P0087 order: low side, then high-pressure pump.
- Replace the sensor only when the gauge disagrees with it and the wiring passed, then clear and verify under load.
Frequently asked questions
Can I drive with a P0192 code?
Not far. The module cannot manage rail pressure without a reading it trusts, and most calibrations limit power or refuse to start. On a diesel it cuts fueling to protect the injectors.
Is P0192 the fuel rail pressure sensor?
Often, but the test is to compare a gauge with the sensor: Audi's procedure calls a difference over 500 kPa a sensor or wiring fault and anything less a real pressure problem. Mazda's Skyactiv bulletin traced P0192 on the 2014 Mazda3 to a high-pressure pump not making pressure, with the sensor reading correctly.
Why did P0192 appear on my CX-9 after a software update?
Because Mazda changed the control logic on 2016 to 2018 CX-9s built before November 2017 so that the engine is no longer power-limited when the low-pressure pump's learned value drifts; instead, P0192 or P0087 is stored when injection is insufficient. The code is the low-pressure pump announcing itself.
How much does it cost to fix P0192?
A wire or connector repair is under an hour. A rail pressure sensor is a moderate part with a short replacement, more when it sits under the valve cover. A high-pressure pump is a major part, which is why the gauge comparison comes first.
Related codes
- P0190 / P0191 / P0193 / P0194: the rest of the sensor family; see P0194.
- P0087 / P0088: rail pressure too low or high; see P0087.
- P0641: sensor reference voltage A circuit, when the shared reference is the cause.
- P119A (Audi): fuel pressure sensor malfunction, on the same bulletin.
The code number itself tells you the family and the domain; how to read an OBD2 code number explains what each character means.