OBD Guide
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P0412

AIR System Switching Valve A Circuit

P0412 is an OBD-II diagnostic trouble code meaning: AIR System Switching Valve A Circuit. Common causes: faulty air a solenoid switch valve, open or shorted valve wiring. Estimated repair cost: $6–222.

Severity
✅ Low
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$6–222 (est.)

Symptoms

  • Check Engine Light Is On
  • Increased CO and HC emissions during cold start
  • Emissions inspection failure
  • Noise or whistle when starting the engine (if the valve is stuck)
  • Otherwise the engine runs fine

Causes

  • Faulty AIR A solenoid switch valve
  • Open or shorted valve wiring
  • Damaged or oxidized valve connector
  • Faulty secondary air pump
  • Clogged hoses or tubes of the AIR system
  • AIR pump relay malfunction
  • ECU malfunction (rare)

How to Fix

  1. Read all error codes with a diagnostic scanner
  2. Check the power supply and grounding of the AIR A switch valve connector
  3. Check the integrity of the wiring from the computer to the valve
  4. Measure the valve solenoid winding resistance (usually 20-30 ohms)
  5. Check the operation of the AIR pump relay
  6. Inspect the hoses and tubes of the system for clogging and cracks
  7. Replace switching valve A if fault is confirmed
  8. Reset the code and do a cold start to check

Related codes

P0410P0411P0413P0414P0415P0416P0417

Error P0412 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0412 code mean?

P0412 is an OBD-II diagnostic trouble code that indicates: AIR System Switching Valve A Circuit

What causes a P0412 error code?

The most common causes of P0412 include: Faulty AIR A solenoid switch valve; Open or shorted valve wiring; Damaged or oxidized valve connector; Faulty secondary air pump.

How do I fix a P0412 diagnostic trouble code?

To fix P0412: Read all error codes with a diagnostic scanner. Check the power supply and grounding of the AIR A switch valve connector. Check the integrity of the wiring from the computer to the valve. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0412?

Do not drive — repair immediately

How much does it cost to fix P0412?

The estimated repair cost for P0412 is $6–222. Actual cost depends on your vehicle, location, and labor rates.

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