Exhaust Pressure Sensor "A" Circuit High
The exhaust pressure sensor is reporting a signal voltage that is higher than the PCM expects, indicating a circuit fault or sensor failure. This prevents the engine control system from accurately monitoring exhaust backpressure, which affects turbocharger boost control and particulate filter regeneration.
What You Might Notice
- Check engine light illuminated
- Lack of engine power or reduced performance
- Inability to perform active regeneration (soot burn-off)
- Rough idle or hesitation during acceleration
- Potential limp mode activation
Most Common Causes
- 1
Exhaust pressure sensor shorted internally
The sensor has failed internally with a short to voltage, causing it to send a constantly high signal to the PCM. This is the most common failure mode for this code.
- 2
Signal circuit shorted to voltage
The wiring between the exhaust pressure sensor and PCM has a short to positive voltage, creating an artificially high sensor reading. This may result from damaged insulation or a pinched wire.
- 3
Open ground circuit to sensor
A break in the ground connection prevents the sensor from establishing a proper reference voltage, causing the signal line to float high. Check for corroded or loose ground connectors.
- 4
PCM module failure
A faulty powertrain control module may misinterpret normal sensor signals as high input, though this is extremely rare and typically only diagnosed after other causes are eliminated.
How to Diagnose It
- 1
Check Exhaust pressure sensor shorted internally — The sensor has failed internally with a short to voltage, causing it to send a constantly high signal to the PCM. This is the most common failure mode for this code.
- 2
Check Signal circuit shorted to voltage — The wiring between the exhaust pressure sensor and PCM has a short to positive voltage, creating an artificially high sensor reading. This may result from damaged insulation or a pinched wire.
- 3
Check Open ground circuit to sensor — A break in the ground connection prevents the sensor from establishing a proper reference voltage, causing the signal line to float high. Check for corroded or loose ground connectors.
- 4
Check PCM module failure — A faulty powertrain control module may misinterpret normal sensor signals as high input, though this is extremely rare and typically only diagnosed after other causes are eliminated.
How to Fix It
- 1
Replace exhaust pressure sensor
Remove and replace the faulty exhaust pressure sensor with an OEM or equivalent unit. Locate the sensor in the exhaust manifold or DPF assembly, disconnect the electrical connector, and unscrew the sensor. Install the new sensor with appropriate torque specifications.
- 2
Repair or replace sensor wiring harness
Inspect the signal and ground wires between the sensor and PCM for damage, corrosion, or shorts. Repair any damaged insulation with appropriate wire repair techniques or replace the entire harness if severely damaged.
- 3
Clean and secure ground connections
Locate the ground point for the exhaust pressure sensor circuit and clean any corrosion from the connector and terminal. Reattach the ground wire securely and apply dielectric grease to prevent future corrosion.
- 4
Clear code and perform test drive
After repairs are completed, use a scan tool to clear the P0473 code and monitor live sensor data during a test drive. Verify that exhaust pressure readings are now within normal operating range (typically 0-5 inches of water column).
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