P0479
PPowertrainExhaust Pressure Control Valve A Intermittent
What does this code mean?
Severity : MediumP0479 signals intermittent operation of exhaust pressure control valve A. This valve, mostly found on diesels, regulates exhaust back pressure, for example to speed up warm up or act as an exhaust brake. The engine control module detects a signal or response that drops out from time to time.
Symptoms
- Check engine light on.
- Slower warm up in cold weather.
- Intermittent loss of power.
- Exhaust brake not working on equipped vehicles.
Possible causes
- Damaged or loose valve connector or wiring.
- Valve sticking due to carbon build up.
- Faulty valve actuator.
- Faulty exhaust pressure sensor.
- Blocked or cracked pressure line.
Diagnosis and repair
- Inspect the connector and wiring while wiggling the wires.
- Check the valve moves freely and is not heavily carboned.
- Command the valve with a scan tool and watch exhaust pressure.
- Test the pressure sensor and its line.
- Clean or replace the faulty part, clear the code and road test.
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Code
P0479
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012