P047C

What it means

P047C is a generic code meaning the engine control unit has seen a voltage on the Exhaust Pressure Sensor B circuit that is lower than the expected range. This usually points to a short to earth, an open circuit, a lost supply or a failed sensor. Which physical sensor is 'B' (for example a particular bank or position in the exhaust, upstream of the turbo or elsewhere) depends on the model and engine, so check the manufacturer's documentation.

Symptoms

• Engine management warning light on
• Reduced power or the car going into limp mode
• Poor or erratic turbocharger boost response
• Rough running or hesitation under load
• Increased smoke or poor fuel economy
• Possible failed regeneration or other related fault codes stored

Possible causes

• Exhaust pressure sensor B failed internally, giving a low signallikely
• Signal wire shorted to earth or chafed against bodywork or the enginelikely
• Damaged, corroded or loose connector at the sensor or control unitlikely
• Open circuit or high resistance in the signal or 5 volt reference supply wirepossible
• Blocked, split or disconnected sensing pipe or heat-damaged wiring near the exhaustpossible
• Fault in the engine control unit's sensor supply or input circuitrare

How to diagnose

1. Read all stored codes and freeze frame data, noting engine load, speed and temperature when the fault set, and look for other sensor supply or exhaust pressure codes
2. Check the manufacturer's information to identify exactly where sensor B is fitted on this engine
3. Inspect the sensor, wiring and connector for heat damage, chafing, corrosion, water ingress and poor pin tension
4. Check any pipe or hose to the sensor for blockage, cracks or disconnection, where one is fitted
5. View live data with the engine off and at idle, and compare the sensor B reading with the other exhaust pressure sensor and with ambient pressure
6. Back-probe the sensor connector to check the reference supply, earth and signal voltages against specification
7. Wiggle-test the harness with live data on screen to find intermittent shorts or opens, then check continuity and insulation to earth with the control unit disconnected
8. Clear the code and road test to see whether it returns, confirming the repair under similar conditions

How to fix

• Replace exhaust pressure sensor B if it reads incorrectly with a good supply and wiring
• Repair or replace the damaged wiring where it is shorted, chafed or open circuit
• Clean, repair or replace the faulty connector and terminals
• Clear or replace the sensing pipe where one is fitted and found blocked or damaged
• Repair or replace the control unit only after wiring and sensor faults have been fully ruled out

Can I keep driving?

Nearby codes

• P047BGenericExhaust Pressure Sensor B Circuit Range/Performance
• P047DGenericExhaust Pressure Sensor B Circuit High