Powertrain, generic (extended)

P2A98 Alternative Fuel Tank Select Valve B Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A98 appears when the voltage on the control circuit of tank select valve B stays higher than the module allows for the commanded state. A ground-switched valve with an interrupted winding or lead shows this pattern, as does a wire that has picked up battery voltage. The valve will then not move on command, and the system keeps drawing from whichever vessel the resting valve connects. In Westport's two-vessel design with a single pump, that means one tank is used up and the second is never reached, so the engine runs short of gas while the gauge still shows reserve. CARB's heavy-duty rule expects such circuit faults to be detected and stored separately. No manufacturer publishes P2A98. A coil resistance check at the valve plug separates a dead coil from a wiring fault.

Likely causes

Interrupted winding or lead at valve B
Control line of valve B in contact with battery voltage
Corrosion at the valve B connector raising resistance

Symptoms

  • Malfunction lamp on
  • Second vessel never used, gas runs out early
  • Gauge shows reserve while power drops

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 bwiring harnessafcm

Related codes

P2A95P2A96P2A97P2A94P2A9C

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