OBD-II code · Powertrain (manufacturer / generic)
P340C Deactivation/Exhaust Valve Control Circuit Bank 1
Generic electrical fault on the cylinder deactivation/exhaust valve control circuit on bank 1. The exhaust control valve modulates exhaust backpressure or routing (EGR feed, sound, regen support); a malfunction shifts torque mapping and may trigger limp mode.
Is it safe to drive with P340C?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyDeactivation solenoid failed
- PossibleWiring break or unplugged connector
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1.5–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Cylinder Deactivation Solenoid, Actuator Wiring
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.