P0412 code meaning
AIR System Switching Valve A Circuit
Powertrain system Generic code P04xx codes Check engine light
What P0412 means
The switching valve is the electrically driven valve of this path – a solenoid valve, or on Pierburg/VW systems an electric changeover valve that applies vacuum to the pneumatic combination valve; valve A serves the first path or bank 1, valve B the second. P0412 is the general electrical fault in the control circuit of valve A, detected by comparing the driver's feedback with its commanded state. GM has used it since about 2015 specifically for an open circuit (200 kΩ or more, 20 of 25 samples, MIL after two trips) and reports shorts as P041F and P044F; older GM systems and Toyota use it for any driver fault. The valve then stays shut, so secondary air is missing and P0411 or P2441 may follow.
P0412 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0412
- Check engine light on
- Secondary air inactive
- Secondary air readiness not set (emissions test)
- Driving normal
Common causes of P0412
- Most likelySwitching valve A faulty (coil open or shorted, water ingress)
- Most likelyConnector corroded or wire open or chafed
- PossibleValve supply missing (fuse, main relay)
- Less likelyDriver in the engine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Air switching valve aAir combination valveValve wiringEngine control module
What each part of P0412 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 12 | The exact fault in that area. |
What to do next
- Note P0412 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 P0412
What does P0412 mean?
P0412 means "AIR System Switching Valve A Circuit". The switching valve is the electrically driven valve of this path – a solenoid valve, or on Pierburg/VW systems an electric changeover valve that applies vacuum to the pneumatic combination valve; valve A serves the first path or bank 1, valve B the second. It is a generic code, so it means the same on every make.
Is it safe to drive with P0412?
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 P0412 fail an emissions test?
Yes, it can. P0412 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 P0412 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0412 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.