Code
P0474
GWM
P — Powertrain
- Exhaust Gas Pressure Sensor Fault
AI status
Completed
Completed
100%
Causes
- Damaged or failed exhaust gas pressure sensor
- Open, shorted, corroded or chafed wiring/connector between sensor and ECM
- Poor or missing sensor reference voltage or ground
- Exhaust leaks or restrictions causing abnormal pressure readings
- Contamination or clogging at sensor port (soot, carbon, debris)
- Faulty ECM (less common)
Symptoms
- MIL/Check Engine light illuminated
- Reduced engine performance, limp mode, or derate in some vehicles
- Poor fuel economy
- Unusual exhaust backpressure or noises (chugging, whistle)
- DPF regeneration issues or frequent regen attempts
- Intermittent or permanent fault stored in engine computer
What to check
- Read freeze frame and live data with a scan tool to confirm P0474 and capture sensor values
- Visual inspection of sensor, connector and wiring for heat damage, corrosion, or soot
- Check for exhaust leaks, loose clamps, damaged flex pipe or cracked manifold upstream of sensor
- Inspect sensor sampling port for soot or blockage; remove and visually inspect if serviceable
- Verify there are no related codes (EGR, DPF, MAP, boost) that could indicate related system faults
Signal parameters
- Typical reference voltage (Vref) to sensor: ~5.0 V (verify exact spec for vehicle)
- Normal sensor output: ~0.5–4.5 V depending on pressure (manufacturer-specific)
- Typical measured pressure range: 0–200 kPa gauge (vehicle-specific)
- Expected steady response to changes in engine load; no abrupt spikes or out-of-range readings
- Response time: sensor output should change smoothly within 50–200 ms when pressure changes
Diagnostic algorithm
- Connect a capable scan tool and record freeze frame/live data for exhaust pressure sensor with key on and engine running; note sensor voltage and reported pressure
- Compare sensor reading to expected values from manufacturer; look for stuck, intermittent, zero, or out-of-range values
- Visually inspect sensor, wiring and connector for heat damage, melted insulation, corrosion, or crushed pins; repair any obvious damage
- Backprobe the sensor connector and check: a) presence of reference voltage (typically ~5 V), b) a good ground, c) sensor output signal with ignition on and changes with engine and exhaust load
- If wiring checks fail, perform continuity and resistance checks between sensor connector and ECM; repair open/shorted wiring or connectors
- If wiring is good, remove sensor (if serviceable) and inspect/clean sampling port; replace if contaminated or damaged
- If available, apply a calibrated pressure source (or use a vacuum/pressure pump where applicable) to the sensor while monitoring output to verify correct response and linearity
- Inspect for exhaust restrictions or leaks (manifold, downpipe, DPF, catalytic converter) that could cause abnormal pressures; repair as needed
- If sensor and harness test correctly but code persists, consider ECM data or perform ECM connector and power/ground checks; replace ECM only after all other causes are excluded
- Clear codes and perform a road test while monitoring live data to confirm the fault is resolved
Likely causes
- Failed exhaust gas pressure sensor due to heat/soot exposure
- Broken or shorted harness near exhaust or turbo (heat-damaged insulation)
- Connector pins corroded or pushed out from sensor connector
- Blocked sensor sampling port from soot/DPF/catalyst material
- Exhaust leak upstream of sensor altering measured pressure
Fault status
Status
Exhaust Gas Pressure Sensor Circuit — range/performance fault detected (P0474).
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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