Powertrain, generic (extended)

P237C Exhaust Heat Exchanger Exhaust Bypass Valve A Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Some hybrids route the exhaust through a coolant heat exchanger after a cold start to warm the engine and cabin sooner, and flap A sends the gas around it once heat is no longer wanted. P237C is set when the drive circuit of that bypass actuator shows an open or a general circuit fault. Ford uses it on its full hybrids: on the Maverick 2.5L of 2022 and 2023, SSM 51921 traces P237C with P237D and P2C22 to water inside the heat exchanger, which is replaced; on 2021–2023 F-150 3.5L PowerBoost trucks built up to 1 March 2023, SSM 52050 blames the bypass control valve and replaces the muffler inlet pipe, while SSM 53003 offers an actuator kit. The bulletins report the MIL lit. P237D and P237E narrow the fault to low or high; P23A2 is valve B.

Likely causes

Water inside the heat exchanger assembly or actuator (Ford Maverick SSM 51921)
Bypass valve actuator with open winding or failed electronics
Broken wire or loose connector in the hot area under the vehicle

Symptoms

  • Check engine light on
  • Engine and cabin may warm up more slowly in cold weather
  • Further heat exchanger codes such as P2C22 stored alongside

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 heat exchangerexhaust bypass valve aexhaust heat recovery actuator

Related codes

P237DP237EP237FP23A2P2C22P2C23

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