Powertrain, generic (extended)

P2258 AIR System Control A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2258 reports that the line controlling secondary air (AIR) pump A or its relay sits at too high a level, usually because it is shorted to battery voltage or the driver cannot pull it down. The pump only runs briefly after a cold start to heat the catalyst faster, so the fault mainly raises warm-up emissions. GM's 2018 tables (LWE section) check it while the low-side driver is switched on: 0.5 ohm or less between signal and supply, in 20 of 25 samples of 250 ms, Type B with the MIL after two trips. VW's 2014 book for the Touareg 3.0 TSI (CGFA) gives a signal current of 0.60 to 2.40 A as criterion. Ford names P2258 beside P0412 as a secondary air fault that disables its catalyst temperature model. P2257 is the low counterpart; P2259/P2260 belong to circuit B.

Likely causes

Control wire of the AIR pump relay chafed through and touching a battery-voltage feed
Secondary air relay with shorted coil or welded contacts
Moisture or corrosion in the relay or pump connector bridging terminals
Faulty output stage in the engine control module

Symptoms

  • MIL on, often without any noticeable change in driving
  • Secondary air pump silent after a cold start
  • Higher hydrocarbon emissions during warm-up, possibly a failed emissions test

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

P2257P0418P0412P2260P0411

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