P0412

Secondary Air Injection System Switching Valve "A" Circuit

Severity: Low
Driving: Drivable — book it in

A fault in the circuit for secondary air injection switching valve "A". The switching valve is what routes the pump's air into the exhaust, and closes to keep exhaust gas out again once the system has finished its cold-start run. A circuit fault here means the module cannot operate the valve.

Possible causes

CommonFailed switching valve solenoid
CommonCorroded connector at the valve
CommonWiring damage between the module and the valve
PossibleBlown fuse on the circuit
PossibleVacuum hose failure on a vacuum-operated valve
RareFailed control module driver

What you might notice

Check engine light on
Failed emissions test
Secondary air system inoperative
Usually no symptom the driver notices

What to check, in order

Inspect the connector at the valve. It sits in a hot area near the exhaust and its connector suffers for it.
Measure the valve solenoid resistance against specification.
On a vacuum-operated valve, check the vacuum hose is intact and that vacuum reaches the valve when commanded.
Check the fuse for the circuit.
Check the harness for heat and chafe damage where it runs near the exhaust.

Read this code from your own car

Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.

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Where this code sits

B · Body C · Chassis P · Powertrain U · Network and communication

Auxiliary emission controls