P0473 - Exhaust Pressure Sensor "A" Circuit High
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0473 is a diagnostic trouble code (DTC) for 'Exhaust Pressure Sensor High Input'. This occurs when the Engine Control Module (ECM) receives a voltage signal from the exhaust back pressure (EBP) sensor that exceeds the calibrated maximum limit (typically >4.8V). The EBP sensor measures exhaust gas pressure before the turbine or DPF. The ECM utilizes this input for VGT (Variable Geometry Turbo) vane control, EGR flow calculations, and DPF soot load monitoring. A 'High' circuit code usually indicates a short to voltage in the signal wire, a loss of ground (floating signal), or an internal sensor failure.
Possible Causes
Faulty exhaust pressure sensor (internal electrical failure)
Open circuit in the sensor ground wire (causing signal to float to reference voltage)
Short to 5V reference on the signal circuit
Blocked or carbon-fouled pressure tube leading to the sensor, or internal ECM failure
Symptoms
Recommended Solution
- Visual Inspection: Check wiring harness and connector for signs of corrosion, melted insulation, or terminal tension. Inspect the metal pressure tube for cracks or blocks.
- Voltage testing: Use a multimeter to verify 5V reference voltage and ground integrity (<0.5 Ohm). If the signal wire shows 5V constant with the sensor unplugged, check for a short to power in the harness.
- Live Data Analysis: Using a scan tool, monitor exhaust pressure values. With the engine off, it should read atmospheric pressure (approx. 14.7 psi or 100 kPa). If it stays at maximum, the circuit is faulty.
- Component Replacement: If the harness and tube are functional but the voltage remains high, replace the exhaust pressure sensor.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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