Powertrain, generic (extended)

P23A7 Exhaust Heat Exchanger Exhaust Bypass Valve B Stuck Closed

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P23A7 is the opposite of P23A6: the second bypass valve (B) on the exhaust heat exchanger does not open on command and stays closed. Depending on the layout, all exhaust is then forced through the heat exchanger even when the engine is fully warm, which adds heat to the coolant and some back pressure – most relevant under load and in hot weather. The module recognises the condition from position feedback or from temperatures that do not follow the command. No manufacturer publishes P23A7, and the valve A version is P00E4. Ford's valve A cases, water inside the heat exchanger (SSM 51921) and a replaceable actuator kit (SSM 53003), are the nearest public examples. CARB requires output components to be checked for proper function. Keep an eye on coolant temperature until it is repaired.

Likely causes

Flap stuck closed by deposits or corrosion
Actuator motor or gearing failed
Damaged or water-filled heat exchanger obstructing the flap

Symptoms

  • Check engine light on
  • Coolant temperature higher than usual under load
  • Possibly reduced power or a changed exhaust note

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–3 h

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

Parts involved

exhaust bypass valve bexhaust heat exchanger

Related codes

P23A6P23A5P23A8P00E4

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