Powertrain, generic (extended)

P237D Exhaust Heat Exchanger Exhaust Bypass Valve A Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P237D concerns the same drive line as P237C, the one that operates bypass flap A of an exhaust heat recovery unit, but here the module measures a voltage that sits too low – the usual picture of a control wire touching ground or an actuator shorted internally. Moisture in a connector under the car can produce exactly that. Ford names P237D in two full-hybrid bulletins: SSM 51921 for 2.5L Maverick hybrids built for model years 2022–23, where water inside the heat exchanger is the cause and the unit is renewed, and SSM 53003 for the PowerBoost F-150 hybrid of model years 2021 to 2023, which points to the heat exchanger actuator and supplies a replacement kit. Both bulletins describe a lit MIL. Unlike P237E, the short goes to ground; with the flap uncontrolled, warm-up can take longer.

Likely causes

Water in the heat exchanger or its actuator shorting the drive (Maverick)
Actuator internally shorted to ground
Control wire chafed through against the body or exhaust bracket

Symptoms

  • Check engine light on
  • Slower heater response after a cold start
  • Car otherwise drives normally

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,500
Time0.5–3 h

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

Parts involved

exhaust bypass valve aexhaust heat recovery actuator

Related codes

P237CP237EP237FP23A3P2C22

References: static.nhtsa.gov, static.nhtsa.gov, en.wikipedia.org.