Powertrain, generic (extended)

P2A4E Alternative Fuel Temperature Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The counterpart to P2A4D: the gas temperature signal rises above its upper limit. With the usual NTC thermistor fed through a pull-up resistor, that equals an absurdly cold reading, and the most frequent reason is an open circuit, either a broken wire, a loose terminal or a sensor that has gone open inside. A short to a voltage source has the same effect. In TransEco's list the related rail temperature High code is attributed to exactly these causes and handled like the Low case, with a substitute value from the intake air sensor or a forced change to petrol. No manufacturer documents P2A4E publicly. Bridging the two pins at the plug should flip the reading to very hot; if not, the break lies between plug and module.

Likely causes

Broken wire or loose terminal in the sensor circuit
Thermistor open internally
Signal wire shorted to a voltage source

Symptoms

  • Check engine light
  • Live data shows gas temperature at its coldest limit
  • Bi-fuel vehicle falls back to petrol

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–450
Time0.5–2 h

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

Parts involved

alt fuel temperature sensorwiring harnessafcm

Related codes

P2A4BP2A4DP2A4FP01B7P0183

References: law.cornell.edu, http:.