P340CDeactivation/Exhaust Valve Control Circuit Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P340C concerns a separate electrical circuit that disables the exhaust valves of bank 1 as a group. A fault in its wiring, connector or actuator coil sets the code. No manufacturer documents it publicly, and none of the known production systems needs it: GM's DFM engines feed the intake and exhaust lifters of each cylinder from one shared solenoid, and a GM patent application describes one hydraulic valve per pair of cylinders that drops the exhaust valves before the intake valves purely by cam timing. Under CARB rules every output of this type needs an electrical integrity test. The intake-side circuit is P340A, bank 2 exhaust P340D, the bank 1 exhaust function P341C. Drivers mainly see the lamp; deactivation is suspended.
- What you may notice
- Check engine lamp on
- Reduced-cylinder mode not available
- Likely causes
- PossibleOpen or shorted wire in the bank 1 exhaust actuator circuit
- PossibleExhaust deactivation actuator coil open or shorted
- RareConnector or wiring damaged by heat near the exhaust side
- RareEngine control module output stage fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.