Powertrain, generic (extended)

P2A52 Alternative Fuel Vaporizer A Outlet Temperature Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Temperature sensors of this type are usually thermistors whose resistance falls as they get warmer, the same principle Ford describes for the fuel rail sensor of its 2003 bi-fuel CNG trucks. A signal under the lower limit would therefore mean an impossibly hot vaporizer A; in practice the signal line touches ground or the sensor is shorted inside. AC STAG lists this case as a reducer temperature sensor short. The danger is that a hot reading could let gas flow into a unit that is actually cold, so a control module will normally replace the value or fall back to petrol. No manufacturer documents P2A52. Pull the plug and watch the live data: a swing to very cold clears the harness, a hot value that remains points to a short in the wiring.

Likely causes

Signal wire shorted to ground
Sensor shorted internally
Moisture or coolant in the connector

Symptoms

  • Check engine light, depending on calibration
  • Gas mode blocked, vehicle runs on petrol
  • Live data shows an implausibly hot vaporizer

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 vaporizer a outlet temp sensorwiring harnessafcm

Related codes

P2A50P2A51P2A53P2A54P2A57

References: law.cornell.edu, static.nhtsa.gov, mystag.pl.