Powertrain, generic (extended)

P2257 AIR System Control A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2257 concerns the control circuit of the secondary air (AIR) pump or its relay, which blows fresh air into the exhaust during cold starts so the catalyst lights off sooner. The code sets when that circuit reads low. GM's 2018 tables (LWE section) watch the low-side driver of the AIR pump control: a resistance of 0.5 ohm or less to controller ground, detected as low voltage with the driver switched off, in 20 of 25 samples of 250 ms with at least 11 V on the powertrain relay, Type B; some controllers also log P0418. VW's 2014 specification books for the CC and Touareg flag a relay control voltage between 0 and 3.26 V. P2258 is the short to power, P0418 the open circuit. Affected cars mainly emit more during warm-up.

Likely causes

Relay control wire shorted to ground
Secondary air relay with a shorted coil
Water ingress in the relay or pump connector

Symptoms

  • Check engine light
  • Secondary air pump silent during cold start
  • Secondary air flow codes such as P0411 may follow

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–400
Time0.5–2 h

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

Parts involved

secondary air pumpsai relaysai wiring

Related codes

P2258P0418P2259P0411

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.