P237E is logged when the driver for exhaust bypass flap A on a heat recovery unit sees a control voltage above its expected range. The likely story is a short from the control wire to a supply feed or an actuator whose internal driver has failed in a way that pulls the line up. The flap then no longer follows the warm-up strategy. Ford is the one maker that names the code publicly, and only once: SSM 53003 lists P237E together with P237C, P237D, P237F, P2C22 and P2C23 for 2021–2023 F-150 hybrids with the 3.5L PowerBoost and blames the actuator mounted on the heat exchanger, which is replaced with a service kit after normal diagnosis. A lit MIL is reported. P237D is the low-side mirror image and P23A4 the same fault on valve B; a high signal rarely heals by itself.
Medium severity. Can I keep driving?You can usually keep driving in the short term. If you smell exhaust fumes in the cabin, stop driving and ventilate the car.
Symptoms
- Check engine light on
- Cabin heat may build up later on cold days
Most likely causes
- Heat exchanger bypass actuator with failed internal driver (Ford F-150 SSM 53003)
- Control wire shorted to a supply circuit in the harness
- Heat-damaged connector with bridged pins
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It affects emissions.
What each character of P237E means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 3: Ignition and misfires
- 7E: Specific fault in that system
Frequently asked questions
Can I keep driving with code P237E?
You can usually keep driving in the short term. If you smell exhaust fumes in the cabin, stop driving and ventilate the car.
What causes code P237E?
The most common causes are: heat exchanger bypass actuator with failed internal driver (Ford F-150 SSM 53003); control wire shorted to a supply circuit in the harness; heat-damaged connector with bridged pins.
Related codes
- P237CExhaust Heat Exchanger Exhaust Bypass Valve A Control Circuit/Open
- P237DExhaust Heat Exchanger Exhaust Bypass Valve A Control Circuit Low
- P237FExhaust Heat Exchanger Exhaust Bypass Valve A Control Performance
- P23A4Exhaust Heat Exchanger Exhaust Bypass Valve B Control Circuit High
- P2C23Exhaust Heat Exchanger Exhaust Bypass Valve A Position Sensor Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.