P0472: Exhaust Pressure Sensor A Circuit Low

What it means

The exhaust pressure sensor A circuit signal is lower than expected. Possible causes include a wiring or connector fault, a sensor fault, or a pressure-passage issue.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Exhaust pressure sensor A sends a signal representing pressure in its exhaust passage to the control module. This code sets when the signal voltage is lower than the module expects, often because the signal is pulled toward ground or the sensor circuit has excessive resistance.

Common causes

Most likely first.

1. Short to ground
2. Connector pins corroded - high contact resistance
3. Harness chafing through insulation

Symptoms

• Check-engine light on
• Possible reduced engine power
• Possible increased exhaust smoke
• Possible reduced fuel economy

How to diagnose it

1. Record freeze-frame data and check sensor A's live reading to confirm whether the low signal is constant or tied to a particular operating condition.
2. Inspect sensor A's connector for corrosion, moisture, bent terminals, or poor terminal contact that could add resistance.
3. Check the sensor A harness for chafing, especially where insulation could be worn through and the signal wire could contact ground.
4. Inspect the pressure tube and passage for blockage or damage, then compare the reading with the expected conditions in service information.
5. Test sensor A's supply, ground, and signal circuit for a short to ground or excessive resistance using the wiring diagram and manufacturer's specification.
6. If the wiring and pressure path are sound, test sensor A and replace it if it produces a low signal outside the manufacturer's specification.

Common fixes

• Clean and secure the sensor A connector; repair corroded or loose terminals.
• Repair chafed wiring or a signal wire shorted to ground.
• Clear a blocked pressure passage or repair a damaged pressure tube.
• Restore a poor sensor ground or other circuit connection.
• Replace exhaust pressure sensor A if it still outputs a low signal with a sound circuit.

Can I keep driving?

A gentle drive may be possible if the engine runs normally, but avoid towing or hard acceleration if power is reduced or exhaust smoke increases. The low reading may disrupt exhaust-system control and emissions performance, so have the circuit checked promptly.