OBD-II code · Powertrain (generic, extended)
P23A4 Exhaust Heat Exchanger Bypass Valve B Control Circuit High
Same as P237E on bypass valve B. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P23A4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl line shorted to supply
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Exhaust Bypass Valve B
Related codes
- P237EExhaust Heat Exchanger Bypass Valve A Control Circuit High
- P23A1O2 Sensor Exhaust Sample Error Bank 2 Sensor 2
- P23A2Exhaust Heat Exchanger Bypass Valve B Control Circuit Open
- P23A3Exhaust Heat Exchanger Bypass Valve B Control Circuit Low
- P23A5Exhaust Heat Exchanger Bypass Valve B Control Performance
- P23A6Exhaust Heat Exchanger Bypass Valve B Stuck Open
- P23A7Exhaust Heat Exchanger Bypass Valve B Stuck Closed
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.