Powertrain, generic (extended)

P24AB EGR Cooler Coolant Pump Stuck On

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24AB is set when the EGR cooler coolant pump keeps running although the controller has switched it off, seen for instance in continued speed feedback or current draw. Causes include a driver stage or relay that stays closed, a short that bypasses the switching side, or pump electronics that ignore the command. For the driver this is less urgent than a pump that will not run, but a constantly running pump drains the battery after shut-off and can slow engine warm-up. Public documentation of this check by a carmaker was not found; it follows from CARB's demand that switched outputs be verified in operation. P24A8 covers the opposite failure, P24A9 a short to ground that may keep the pump running.

Likely causes

Relay or controller output stage stuck closed
Short in the harness bypassing the switched side
Pump electronics no longer responding to the command

Symptoms

  • Pump audible after engine shut-off
  • Battery drained after standing
  • Malfunction indicator lamp on

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–500
Time0.5–2 h

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

Parts involved

egr cooler coolant pump

Related codes

P24A8P24A9P24AA

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