Exhaust Pressure Sensor Circuit Low
The P047C code indicates that the Engine Control Module (ECM) has detected a voltage signal from the exhaust pressure sensor that is lower than the expected range. This sensor monitors backpressure in the exhaust system, often used for diesel particulate filter (DPF) regeneration and EGR control. A low circuit condition can be caused by a faulty sensor, wiring issues (short to ground, open circuit), or a problem with the ECM. This code is common in diesel vehicles, especially those with DPF systems.
1. Most Common Causes
- Faulty exhaust pressure sensor
- Short to ground in sensor circuit
- Open circuit in sensor wiring or connector
- Corroded or damaged sensor connector
- Failed ECM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Poor fuel economy
- DPF regeneration issues (if equipped)
- Possible limp mode activation
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the exhaust pressure sensor and wiring for damage, corrosion, or loose connections.
Step 3: Using a multimeter, check sensor signal voltage (typically 0.5-4.5V) at idle and compare to manufacturer specs.
Step 4: Test sensor reference voltage (5V) and ground circuits at the sensor connector.
Step 5: If circuits are good, replace the exhaust pressure sensor and clear codes.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can lead to reduced performance, poor fuel economy, and potential DPF damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, depending on sensor location and vehicle make/model.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.