P0477: Exhaust Pressure Control Valve A Low
What to do
Usually driveable with little noticeable symptom.
What this code means
The exhaust pressure control valve circuit is reading low — generally a short to ground in the control wiring or an actuator winding that has failed short. Disconnecting the actuator and re-measuring identifies which side of the connector the fault lies on.
Likely causes
Start here
- Signal wire shorted to ground · moderate
- Open or shorted solenoid winding · moderate
- Corroded or loose connector · easy
Less common
- Damaged wiring harness near exhaust heat · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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