The EOBD/OBDII error code P0472 indicates a problem with the exhaust pressure sensor, specifically a low input signal. This code applies to vehicles with variable nozzle turbochargers, both gasoline and diesel engines, and has become increasingly common in various makes and models since around 2005. Understanding this code is crucial for accurate diagnosis and repair.
What Does the P0472 Code Mean?
The P0472 code signifies that the exhaust pressure sensor is sending a signal voltage to the Powertrain Control Module (PCM) that is lower than expected. The PCM compares the exhaust pressure sensor reading with the intake manifold pressure or ambient air pressure. A significant discrepancy triggers the P0472 code, pointing to an electrical circuit issue within the exhaust pressure sensor system. This differs from the P0471 code, which can indicate both mechanical and electrical faults.
Symptoms of a P0472 Error Code
Recognizing the symptoms associated with a P0472 code can help in early diagnosis. Common symptoms include:
- Illuminated Check Engine Light: The most obvious sign, indicating a detected issue within the engine system.
- Reduced Engine Power: The engine may lack power or feel sluggish due to improper turbocharger function.
- Manual Regeneration Failure (Diesel Engines): Vehicles equipped with Diesel Particulate Filters (DPF) may be unable to perform regeneration, leading to soot buildup.
- Crank No-Start Condition: In severe cases, accumulated soot and continued regeneration failure can prevent the engine from starting.
Common Causes of a P0472 Code
Several factors can contribute to a P0472 error code. These include:
- Open Circuit in Signal Wire: A break or disconnection in the wire between the exhaust pressure sensor and the PCM.
- Open Circuit in Power Supply Wire: Interruption of power supply to the sensor from the PCM.
- Short to Ground in Signal Circuit: The signal wire may be grounded, disrupting the voltage signal.
- Faulty Exhaust Pressure Sensor: Internal short circuits within the sensor can cause low voltage readings.
- Faulty PCM (Rare): While less common, a malfunctioning PCM can incorrectly interpret signals.
Diagnosing and Repairing a P0472 Code
Troubleshooting a P0472 code involves a systematic approach:
- Consult Technical Service Bulletins (TSBs): Check for manufacturer-specific solutions or known issues related to this code.
- Visual Inspection: Examine the exhaust pressure sensor, wiring, and connectors for damage, corrosion, or loose connections. Clean and repair as needed.
- Clear Diagnostic Trouble Codes: Use a scan tool to clear the codes and see if the P0472 code returns after a test drive.
- Test Sensor Circuitry: Use a Digital Volt Ohm Meter (DVOM) to check for voltage and continuity in the power supply, signal, and ground circuits of the sensor. Compare readings to manufacturer specifications.
- Sensor Replacement: If all circuit tests pass, a faulty exhaust pressure sensor is the likely culprit. Replace the sensor and clear the codes.
- PCM Check (Last Resort): If the problem persists after sensor replacement, suspect a potential PCM issue. This requires specialized diagnostic equipment.
Conclusion
The EOBD/OBDII error code P0472 indicates a problem with the exhaust pressure sensor’s low input signal. By understanding the code’s meaning, recognizing the symptoms, and following a logical diagnostic procedure, you can effectively identify and resolve the underlying issue, restoring proper engine function. Remember to consult your vehicle’s specific repair manual for detailed instructions and safety precautions.
