What it means
A general fault on exhaust pressure control valve A — used as a backpressure brake on heavy-duty diesels and to assist DPF regeneration by raising exhaust temperature.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Exhaust pressure control valve A regulates exhaust backpressure when the vehicle is equipped to use it, such as for exhaust braking or to support DPF regeneration. This code sets when the control module detects a general fault in valve A's control circuit or operation.
Common causes
Most likely first.
- Exhaust pressure control valve failure or sticking
- Actuator or solenoid failure
- Open or short in wiring
- Corroded or loose connector
Symptoms
- Check-engine light on
- Reduced exhaust-brake performance, if equipped
- Possible reduced engine power
- DPF regeneration problems or warning, where equipped
How to diagnose it
- Record freeze-frame data and check for related exhaust-brake, actuator, or DPF codes to understand which valve A function is affected.
- Inspect valve A's connector and wiring for looseness, corrosion, heat damage, or an open or shorted section.
- Visually check the valve body, actuator, and accessible linkage for damage, obstruction, or signs the valve is stuck.
- Use scan-tool data or an available actuator test to compare the module's command for valve A with the reported response.
- Test the valve A actuator or solenoid circuit against the wiring diagram and manufacturer's specification.
- If the circuit is sound, test the valve and linkage for sticking or mechanical failure using the vehicle's service procedure.
Common fixes
- Reconnect and secure the valve A electrical connector.
- Clean or repair corroded terminals and damaged valve A wiring.
- Free a sticking valve or repair a binding linkage if service information permits.
- Replace the failed valve A actuator or solenoid.
- Replace exhaust pressure control valve A if the valve itself is faulty.
Can I keep driving?
If equipped with an exhaust brake, assume its braking function may be reduced and leave extra stopping distance; do not rely on it to control speed. Avoid demanding use of the vehicle until repaired, especially if a DPF warning or power loss appears.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.