P3477 code meaning
Cylinder 10 Exhaust Valve Control Circuit/Open
Powertrain system Generic code P34xx codes Check engine light
What P3477 means
P3477 belongs to engines that switch the exhaust valve of cylinder 10 through its own actuator, and it reports that this actuator's circuit is open. No manufacturer documents this code publicly; J2012 reserves the codes for cylinders 9 to 12 for engines with more than eight cylinders. Ten-cylinder engines with shut-off, the Audi R8 V10 and the Lamborghini Huracán, deactivate a bank rather than individual valves; Audi names injection and ignition as what is stopped. GM's patent on valve deactivation shows that the exhaust side has its own timing requirement, with solenoid-driven hydraulic control valves stopping and restarting the exhaust valves ahead of the intake valves. Diagnose as a plain open circuit: connector, wire, coil. P3479 and P3480 are the shorts, P3478 the functional fault, P3473 the intake circuit.
P3477 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 P3477
- Check engine lamp on
- Engine keeps all cylinders active
Common causes of P3477
- PossibleWire to the cylinder 10 exhaust actuator interrupted
- PossibleExhaust actuator coil of cylinder 10 open
- PossibleCorroded actuator connector
- Less likelyControl module output failed
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 P3477 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). |
| 77 | The exact fault in that area. |
What to do next
- Note P3477 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 P3477
What does P3477 mean?
P3477 means "Cylinder 10 Exhaust Valve Control Circuit/Open". P3477 belongs to engines that switch the exhaust valve of cylinder 10 through its own actuator, and it reports that this actuator's circuit is open. It is a generic code, so it means the same on every make.
Is it safe to drive with P3477?
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 P3477 fail an emissions test?
Yes, it can. P3477 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 P3477 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 P3477 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.