Powertrain, generic (extended)

P2A93 Alternative Fuel Tank Select Valve A Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A93 is stored when the module measures a voltage on the control line of tank select valve A that falls short of the level expected for the commanded state. With a low-side driver this usually means the line touches ground, which can energise the solenoid permanently and keep valve A in its switched position regardless of the command. If the valve is fed from the positive side instead, the same fault overloads that output, which then usually switches itself off. In both cases the module can no longer choose the vessel, so the automatic change from an empty tank to a full one, as described in Westport's two-vessel patent, cannot be relied on. Valves near cryogenic lines collect condensation, so water in the connector is a plausible cause. No manufacturer documents P2A93; P2A94 is the high case.

Likely causes

Control wire of valve A chafed through to ground
Condensation or water in the connector of valve A
Shorted turns in the coil of valve A

Symptoms

  • Malfunction lamp on
  • Tank selection stuck, one vessel emptied completely
  • Fuse or output protection of the gas module trips

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 awiring harnessafcm

Related codes

P2A91P2A92P2A94P2A97P2A9B

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