Powertrain, generic (extended)

P2A28 Alternative Fuel Tank Shutoff Valve C Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2A28 tells that the control line of shutoff valve C reads too low. In TransEco Energy's AFCM table the cause is a lead to ground or an interruption; the MIL lights in both dedicated and bi-fuel conversions, and the vehicle continues without a forced change of fuel. Another number, P2A18, appears there alongside. Ford's Boss 302S list of 2014 carries P2A28 too. On cylinders mounted under a truck bed or on a bus roof the harness runs past brackets and clamps, where insulation can wear through. Whether a grounded line leaves the valve shut or pulls it open depends on whether the module switches the supply side or the ground side of the coil. P2A29 covers the high reading, P2A24 the same fault on valve B.

Likely causes

Insulation of the valve C wire worn through at a clamp
Interrupted lead, reported here by some modules
Coil of valve C shorted internally

Symptoms

  • Check engine light
  • Cylinder C not used or not shut off correctly

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,200
Time0.5–3 h

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

Parts involved

alt fuel tank shutoff valve cwiring harnessafcm

Related codes

P2A26P2A27P2A29P2A24P2A2C

References: http:, performanceparts.ford.com, law.cornell.edu.