Powertrain, generic · Auxiliary emission controls

P0419 AIR System Control B Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

After a cold start the secondary air (AIR) pump blows fresh air behind the exhaust valves so that unburnt fuel burns off and the catalyst heats up faster; a shut-off valve opens the path and stops exhaust from flowing back. Control B is the drive circuit of a second pump or pump relay, found only on systems with two pumps or relays, for example large V engines with one pump per bank. It is checked like P0418 by comparing the driver's feedback with its commanded state. No manufacturer document available to us describes P0419 specifically; Pierburg's fault table lists it as relay B with the same remedies as relay A.

Likely causes

Pump relay B faulty
Wire or connector to relay B faulty
Fuse or supply
Pump B blocked (consequential damage)
Engine module

Symptoms

  • Check engine light on
  • Second pump does not run
  • Secondary air readiness not set (emission test)
  • Driving normal

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–700
Time0.2–2.5 h

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

Parts involved

air pump relay bsecondary air pumprelay wiringengine control module

Related codes

P0418P2259P2260P2446P2447

References: techtips.ie, ms-motorservice.com, law.cornell.edu.