P0412: Secondary air switching valve A circuit malfunction
The ECU has found an electrical fault in the circuit of the valve that lets secondary air into the exhaust. Usually the connector, wiring or valve.
| Code | P0412 |
|---|---|
| System | Engine and transmission |
| Group | P04xx, Emissions control |
| Type | Generic: it means the same on every make |
| Can you keep driving? | Yes, no rush |
What P0412 means
Switching valve A opens the path for secondary air to reach the exhaust while the pump is running. The ECU controls it electrically and has seen that its circuit is not responding properly (broken wire, short or damaged coil). Which valve is A is defined by each manufacturer.
Most common causes
- Loose or corroded valve connector
- Broken or chafed wiring
- Failed valve coil
- Fuse or power supply to the circuit
- ECU fault (rare)
Symptoms
- Engine warning light on
- Secondary air stops working
- Failing an emissions test
- Usually no change in how the car drives
Can you drive with P0412?
Yes, no rush It does not affect normal driving. You can keep using the car and fix it when convenient, before the next inspection.
Open the bonnetthe in-depth explanation
How to check it
Find the valve (usually next to the secondary air hoses) and check that its connector is firmly seated and clean. A garage can measure the coil resistance and operate it with their diagnostic tool.
How to read and clear P0412 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0412 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P040E The exhaust gas recirculation temperature sensor A fails now and then
- P040F EGR temperature sensors A and B do not agree
- P0410 Secondary air injection system malfunction
- P0411 Secondary air injection incorrect flow detected
- P0413 The secondary air injection system switching valve A has a broken or
- P0414 The secondary air injection system switching valve A has a short circuit
- P0415 The secondary air injection system switching valve B has an electrical fault
- P0416 The secondary air injection system switching valve B has a broken or
- P0400 Exhaust gas recirculation (EGR) flow malfunction
- P0401 Exhaust gas recirculation (EGR) flow insufficient
- P0402 Exhaust gas recirculation (EGR) flow excessive
- P0403 EGR control circuit malfunction
What does code P0412 mean?
Switching valve A opens the path for secondary air to reach the exhaust while the pump is running. The ECU controls it electrically and has seen that its circuit is not responding properly (broken wire, short or damaged coil). Which valve is A is defined by each manufacturer.
Can you drive with P0412?
It does not affect normal driving. You can keep using the car and fix it when convenient, before the next inspection.
How do you clear P0412?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0412 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
