Powertrain, generic (extended)

P2A97 Alternative Fuel Tank Select Valve B Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A97 indicates that the drive line of tank select valve B reads too low. If the module feeds the valve from the positive side, a short to ground in the wire or a coil with shorted windings drags the output down, and the stage switches off to protect itself, so valve B falls back to its spring position. If the module switches the ground side instead, the same short can hold the valve energised all the time. The practical effect is that the choice of vessel no longer follows the strategy: in the staged scheme Cespira patented for two gas supplies, the controller cannot react when a supply reaches its lower pressure limit. No manufacturer documents P2A97. Look for chafing where the harness crosses tank straps and brackets. P2A98 is the high counterpart.

Likely causes

Wire to valve B chafed against a tank strap or bracket
Shorted windings in the coil of valve B
Moisture bridging the pins of the valve B plug

Symptoms

  • Malfunction lamp on
  • Tank change does not happen or happens at the wrong time
  • Gas mode ends early with fuel still on board

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

P2A95P2A96P2A98P2A93P2A9B

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