OBD-II code · Powertrain (manufacturer / generic)
P3421 Cylinder 3 Exhaust Valve Control Circuit/Open
The engine control module has detected an open or out-of-range circuit at the cylinder 3 exhaust valve deactivation solenoid. Cylinder 3 cannot be deactivated on the exhaust side until the circuit is restored.
Is it safe to drive with P3421?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySolenoid coil open
- PossibleWiring or connector open
- Less likelyPin pushed back out of connector body
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Cylinder Deactivation Solenoid, Engine Wiring Harness, Ecm
Related codes
- P3414Cylinder 2 Exhaust Valve Control Circuit/Open
- P3429Cylinder 4 Exhaust Valve Control Circuit/Open
- P3436Cylinder 5 Exhaust Valve Control Circuit/Open
- P3444Cylinder 6 Exhaust Valve Control Circuit/Open
- P3452Cylinder 7 Exhaust Valve Control Circuit/Open
- P3460Cylinder 8 Exhaust Valve Control Circuit/Open
- P341CDeactivation/Exhaust Valve Control Circuit Performance Bank 1
- P341DDeactivation/Exhaust Valve Control Circuit Performance Bank 2
- P3420Cylinder 3 Deactivation/Intake Valve Control Circuit High
- P3422Cylinder 3 Exhaust Valve Control Performance
- P3423Cylinder 3 Exhaust Valve Control Circuit Low
- P3424Cylinder 3 Exhaust Valve Control Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.