P237E

Code

Generic P — Powertrain

Exhaust Heat Exchanger Exhaust Bypass Valve A Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 23 RU: 17

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Page language: EN

Causes

Open or damaged wiring in the bypass valve control circuit
Short to battery/ignition voltage on the control wire
Corroded or poorly connected valve connector
Failed exhaust bypass valve solenoid
Blown fuse or faulty relay supplying the circuit
Faulty PCM/ECU or its output driver (less common)

Symptoms

Malfunction Indicator Lamp (MIL) or check engine light illuminated
Stored/active P237E DTC (may be accompanied by other related codes)
Reduced or improper operation of exhaust heat exchanger/bypass (longer warm-up, changed exhaust routing)
Possible degraded cold-start emissions or catalyst heating performance
Intermittent fault behavior if connector/wiring is corroded or loose

What to check

Retrieve freeze frame and all related codes with a scan tool; note operating conditions when the code set
Visually inspect connector and wiring to the bypass valve for damage, corrosion, pin deformation, water or oil contamination
Check fuses and relays for the valve circuit
Perform wiggle test on wiring while monitoring live data or test lamp for intermittent changes
Back-probe the valve connector and measure voltages with key ON engine OFF and during commanded operation
Measure coil resistance of the bypass valve solenoid and compare with service specification

Signal parameters

Uncommanded control circuit voltage high — typically battery voltage (~12 V) present at the control pin when the PCM is not commanding it
Expected control signal: either 0 V (ground) or switched 12 V depending on vehicle design; consult OEM wiring diagram
Typical solenoid coil resistance: consult service manual (example ranges often 10–30 ohms); significant deviation indicates open/short
No-voltage/low-resistance short to battery on the control conductor will register as a high-voltage fault

Diagnostic algorithm

Connect a diagnostic scan tool, record P237E and any related codes, note freeze frame data and live parameters for bypass valve state.
Visually inspect the valve and harness for damage, corrosion, water, and secure connector mating. Repair as needed.
Check fuses/relays powering the circuit; replace if blown or faulty.
With connector disconnected, measure resistance across the bypass valve solenoid coil. Compare to service spec; replace valve if out of range or shorted to chassis.
Back-probe the valve control pin at the harness with key ON (engine OFF). Measure voltage relative to chassis ground. Determine normal rest voltage from service data. A high voltage when PCM is not commanding indicates a short to battery or incorrect supply wiring.
Command the valve ON/OFF from the scan tool while monitoring control wire voltage. If the PCM should switch to ground, expect voltage to drop near 0 V when commanded; if it does not, suspect wiring/PCM.
If control wire reads battery voltage only when connected to harness and connector pins look damaged, repair/replace the harness or connector and retest.
Check continuity from the valve control pin back to the PCM pin and continuity/voltage to battery and ground to locate short/open. Repair damaged wiring or terminals.
If wiring and valve check good, test the PCM output driver per manufacturer procedure or substitute known-good PCM if applicable.
Clear codes and perform verification drive/test cycle to confirm repair.

Likely causes

Short to voltage on control wire (pinched/chafed wiring)
Faulty/exposed connector terminals allowing high resistance or intermittent connection
Failed solenoid with internal short or incorrect internal wiring
Blown fuse or relay feeding the circuit
PCM output driver failed

Fault status

⚠️ Status

Control Circuit High — Voltage on the Exhaust Heat Exchanger Exhaust Bypass Valve A control circuit is higher than the expected range; electrical fault detected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours