P3408 code meaning
Cylinder 1 Exhaust Valve Control Circuit High
Powertrain system Generic code P34xx codes Check engine light
What P3408 means
If an engine has its own actuator for the exhaust valves of cylinder 1, P3408 marks a control circuit that reads high, usually a short to battery voltage. No manufacturer documents this code publicly. For comparison, GM checks the intake-side P3404 with the driver switched on and flags under 0.5 ohm to supply. A GM patent application switches intake and exhaust valves together through one shared hydraulic valve, exhaust side first, and describes no separate exhaust channel either. With one solenoid per cylinder, as on GM's DFM, the code is not needed. Siblings: P3405 open, P3406 function, P3407 short to ground; P3404 is the intake-side equivalent.
P3408 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P3408
- Check engine lamp on
- Cylinder deactivation disabled
Common causes of P3408
- PossibleControl wire shorted to a supply voltage
- PossibleShorted coil in the exhaust valve actuator
- Less likelyOutput stage fault in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cylinder deactivation solenoidWiring harnessECM
What each part of P3408 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 3 | Mixed range: generic and manufacturer-specific codes. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 08 | The exact fault in that area. |
What to do next
- Note P3408 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P3408
What does P3408 mean?
P3408 means "Cylinder 1 Exhaust Valve Control Circuit High". If an engine has its own actuator for the exhaust valves of cylinder 1, P3408 marks a control circuit that reads high, usually a short to battery voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P3408?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P3408 fail an emissions test?
Yes, it can. P3408 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P3408 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P3408 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.