Powertrain, generic (extended)

P23A3 Exhaust Heat Exchanger Exhaust Bypass Valve B Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

With P23A3 the module sees the control line of exhaust bypass valve B sitting lower than its commanded state allows, which usually means that the wire or the driver stage of the actuator has found a path to ground. Water or road salt in a connector under the vehicle is a typical trigger. P23A3 itself appears in no public manufacturer document. For the valve A equivalent P237D, Ford's SSM 53003 on 2021–2023 F-150 PowerBoost hybrids blames the actuator mounted on the heat exchanger and supplies service kit PL3Z-5K245-B, while SSM 51921 links the code on Mavericks to water inside the heat exchanger. CARB expects such outputs to be monitored for out-of-range circuit states. If the flap cannot be driven, warm-up may take longer; P23A4 is the opposite short.

Likely causes

Control wire chafed through and touching body or exhaust ground
Moisture or salt bridging pins in the actuator connector
Internal short in the valve B actuator

Symptoms

  • Check engine light on
  • Heater output builds up slowly after a cold start
  • Fault may reappear after rain or washing

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

P23A2P23A4P23A5P237D

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.