Powertrain, generic (extended)

P2A9C Alternative Fuel Tank Select Valve C Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A9C reports a control voltage at select valve C above the level the commanded state permits. The usual reasons are an interrupted coil or wire on a valve the module switches to ground, which leaves supply voltage on the line, or a foreign voltage fed in from a damaged neighbouring wire. Valve C then ignores commands. In a staged strategy like the one Cespira patented, where the controller moves between supplies as their pressures drop below set limits, the step involving vessel C is lost, so its content is either never tapped or cannot be shut out of the sequence. Range falls and the engine may switch to its other fuel sooner. No manufacturer publishes P2A9C. Compare coil resistance with valves A and B where they are identical.

Likely causes

Open coil or wire on ground-switched valve C
Foreign voltage from a damaged neighbouring wire
Corroded terminals at valve C

Symptoms

  • Malfunction lamp on
  • Third vessel never drawn, range reduced
  • Earlier change to the other fuel

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,200
Time1–4 h

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

Parts involved

alt fuel tank select valve cwiring harnessafcm

Related codes

P2A99P2A9AP2A9BP2A94P2A98

References: law.cornell.edu, patents.google.com.