Powertrain, generic · Auxiliary emission controls

P0412 AIR System Switching Valve A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Switching valve A faulty (coil open or shorted, water ingress)
Connector corroded or wire open or chafed
Valve supply missing (fuse, main relay)
Driver in the engine module

Symptoms

  • Check engine light on
  • Secondary air inactive
  • Secondary air readiness not set (emission test)
  • Driving normal

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–350
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

air switching valve aair combination valvevalve wiringengine control module

Related codes

P0413P0414P0415P0411P2440P2441

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, techtips.ie.