Powertrain, generic (extended)

P24CC Reductant Tank Cap Switch Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24CC is a plausibility fault: the cap switch at the DEF filler neck delivers an electrically valid signal, but its behaviour does not match what else the controller knows, for instance a switch that still reports an open cap long after refilling, or one that never changes state while the tank level clearly rose. Audi names the code in bulletin 2051053 (and its revision) for the 2013 to 2015 Q7 TDI, where the AdBlue cap switch on the active tank sticks in hot, humid climates; the bulletin lists it as P24CC00 next to P24CB00 and replaces the switch with an improved part after removing the tank. Because wiring checks pass, the stuck switch itself is the prime suspect. P24CB covers general circuit faults, P24CD and P24CE the electrical extremes.

Likely causes

Switch stuck in one position so it no longer follows the cap
DEF residue hindering the switch plunger
Damaged or non-original filler cap that does not actuate the switch

Symptoms

  • Malfunction indicator lamp on after a DEF refill
  • Fill level or refill message not updated

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–600
Time0.5–3 h

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

Parts involved

reductant tank cap switch

Related codes

P24CBP24CDP24CEP24CF

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.