What it means
A control module has stopped receiving expected network messages from the exhaust pressure control valve A sensor/switch. The effect on exhaust pressure control depends on the vehicle's system design.
At a glance
- Usually lights the warning light of the system that lost communication
- Affects emissions; the car can fail an emissions test
How it works
Exhaust pressure control valve A and its sensor or switch report information used to regulate exhaust pressure. This code sets when a module stops receiving the expected network messages from valve A's sensor or switch, potentially disrupting exhaust pressure control.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
Symptoms
- Warning light or message related to the affected system
- Exhaust pressure control may be affected
How to diagnose it
- Record freeze-frame data and scan all modules for exhaust-pressure and communication codes to establish when valve A messages were lost.
- Check live data for valve A sensor or switch status and compare it with commanded exhaust pressure control, if available.
- Inspect the valve A sensor or switch connector and its network wiring for corrosion, loose pins, heat damage, or chafing near the exhaust.
- Check the associated component or module's power and ground according to the manufacturer's wiring information.
- Test the network wiring to valve A for opens or shorts, then evaluate the sensor, switch, or module if the circuits pass.
Common fixes
- Reconnect or clean the valve A sensor or switch connector.
- Repair heat-damaged or chafed network wiring and connector terminals.
- Restore the associated module's power or ground.
- Replace the valve A sensor, switch, or module that fails checks after wiring and feeds are confirmed.
Can I keep driving?
Drive gently and stop if the vehicle develops severe power loss, excessive exhaust heat, or a new warning indicating a critical fault. Faulty exhaust pressure control can affect engine operation and emissions.
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.