Powertrain, generic (extended)

P23A6 Exhaust Heat Exchanger Exhaust Bypass Valve B Stuck Open

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P23A6 says that bypass valve B of the exhaust heat exchanger stays open while the module wants it closed. In the usual layout the exhaust then keeps taking the bypass route, so the heat exchanger adds little or no heat after a cold start – noticeable as a slow engine warm-up and a weak cabin heater in cold weather, and on hybrids as the engine running longer just to make heat. The fault is judged mechanically, from position feedback or temperature response, not from the wiring. No manufacturer documents P23A6; the valve A twin is P00E3. Ford's valve A bulletins (SSM 52050, SSM 53003) show that faulty bypass valves and worn actuators on these units do occur. CARB requires functional monitoring of such outputs. P23A7 is the reverse case.

Likely causes

Flap seized in the open position by carbon or corrosion
Linkage between actuator and flap broken or detached
Actuator no longer able to move the flap

Symptoms

  • Check engine light on
  • Engine and heater take noticeably longer to warm up
  • Hybrid engine runs more often in cold weather

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

P23A7P23A5P23A8P00E3

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