P23A4Exhaust Heat Exchanger Exhaust Bypass Valve B Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23A4 is stored when the control circuit of exhaust heat exchanger bypass valve B reads higher than expected – a short to a battery feed, a chafed wire touching another supply, or an actuator whose electronics pull the line up. Because the flap no longer obeys, the warm-up strategy has to run without it. There is no public manufacturer documentation for P23A4. Ford names the valve A counterpart P237E only once, in SSM 53003 for 2021–2023 F-150 hybrids with the 3.5L PowerBoost, together with the position sensor codes P2C22 and P2C23, and replaces the heat exchanger actuator. CARB requires circuit checks on emission-related output components. P23A3 is the low-side fault and P23A2 the open circuit; a high reading seldom clears by itself.
- What you may notice
- Check engine light on
- Bypass flap does not respond to an actuator test
- Driving behaviour unchanged
- Likely causes
- LikelyControl wire shorted to a 12 V feed in the harness
- PossibleFailed electronics inside the valve B actuator
- RareOutput stage in the controlling module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.