Powertrain, generic (extended)

P23A2 Exhaust Heat Exchanger Exhaust Bypass Valve B Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P23A2 reports an open or otherwise broken drive circuit for the second exhaust bypass flap, valve B, of an exhaust heat exchanger. Such units route the exhaust through a coolant heat exchanger after a cold start and send it past once engine and cabin are warm; a valve B only exists where the layout needs two flaps. No manufacturer documents P23A2 publicly. The closest published case is Ford's valve A on its full hybrids: SSM 51921 (Maverick 2.5L) and SSM 52050 (F-150 3.5L PowerBoost) treat the matching code P237C with a lit MIL and a new heat exchanger or muffler inlet pipe. CARB requires emission-related output components to be checked for circuit faults. P23A3 and P23A4 narrow the fault to low or high; P237C is valve A.

Likely causes

Connector at the valve B actuator loose, corroded or unplugged
Control wire broken near the hot exhaust or at a harness clip
Actuator coil or internal electronics of valve B open

Symptoms

  • Check engine light on
  • Slower engine and cabin warm-up in cold weather
  • No change in how the vehicle drives

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,200
Time0.5–3 h

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

Parts involved

exhaust bypass valve bexhaust heat recovery actuator

Related codes

P23A3P23A4P23A5P237CU066C

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, en.wikipedia.org.