What does it mean?
P3423 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 3 Exhaust Valve Control Circuit Low . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- MIL (check engine lamp) lit, and the code often resets shortly after clearing
- Exhaust valve control stuck in its default position, leaving the engine flat under acceleration
- Rough idle with noticeable vibration through the body
- Persistent valve train ticking that does not respond to commands
- Higher fuel consumption and possible cylinder 3 misfire
- Reduced power or limp mode on some vehicles
Likely causes
- Control wire grounded through a chafe point against the head, a heat shield or a bracket
- Solenoid coil shorted internally to its housing
- Oil or moisture inside the connector creating a leakage path to ground
- Harness crushed or pinched during earlier engine work
- PCM (powertrain control module) output driver shorted on and holding the line low
- Aftermarket or previously repaired splice in this circuit that has grounded out
How to fix it
- Check for other low-side codes on the same bank; several together point to a shared harness section
- Unplug the cylinder 3 exhaust solenoid and see whether the fault changes to an open circuit code
- With both the solenoid and module disconnected, measure resistance between the control wire and engine ground
- Trace the harness past every clip, bracket and heat shield looking for rub-through and crush marks
- Compare the coil resistance with a matching solenoid on the engine
- Repair or reroute the damaged wiring, or replace an internally shorted solenoid
- Clear the code, command the output with the scan tool and road test to confirm the circuit behaves normally