P0412

AIR System Switching Valve A Circuit

Q: Is it safe to drive with P0412?

Yes — the secondary air system only affects cold-start emissions, so the engine drives normally. You'll need it fixed to pass an emissions test, though.

Q: Can I just clear P0412?

It will return until the valve or its circuit is repaired, and the emissions monitor won't pass with the fault present.

Secondary air injection (emissions) Generic OBD-II Medium

What it means

P0412 means the ECM has detected an electrical fault in the secondary air injection switching valve A circuit. This valve routes fresh air into the exhaust at cold start to help the catalytic converter warm up and cut emissions. The engine drives normally, but the fault will trigger the check-engine light and cause an emissions-test failure.

Medium

Can I keep driving? The engine drives normally — the main consequences are a check-engine light and a failed emissions test.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Failed emissions test
Usually no change in how the engine drives
Possible brief rough idle only during cold start when secondary air runs

Common causes

Most likely first

Faulty secondary air injection switching valve A (solenoid)Likely
Open or shorted wiring in the switching valve control circuitCommon
Poor or corroded connector at the valveCommon
Faulty relay or fuse feeding the secondary air systemLess often
Faulty ECM (least likely)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the fault is the secondary air switching valve A circuit.
Inspect the valve's connector and control wiring for damage or corrosion.
Check power, ground, and the ECM control signal at the valve.
Test the switching valve solenoid's resistance against specification.
Replace the valve or repair the wiring as indicated. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0412?+

Yes — the secondary air system only affects cold-start emissions, so the engine drives normally. You'll need it fixed to pass an emissions test, though.

Can I just clear P0412?+

It will return until the valve or its circuit is repaired, and the emissions monitor won't pass with the fault present.

Read & clear P0412 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX