P23C3

Code

Generic P — Powertrain

Engine Coolant Bypass Valve C Position Sensor Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 35 RU: 26

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Open or short in position sensor wiring (broken conductor, chafing to ground, short to battery)
Corroded, loose or damaged connector at the valve or ECM
Failed/contaminated bypass valve position sensor
Stuck or mechanically seized bypass valve preventing correct sensor movement
Faulty ground or supply voltage to the sensor
Intermittent wiring fault (pinched harness, water intrusion)

Retrieve and record freeze frame and live data for bypass valve C position and related coolant temperature PIDs
Scan for related codes (other bypass valve position codes, coolant temp codes, communication errors)
Visual inspection of valve, sensor, and harness for damage, corrosion, or contamination
Check connector mating surfaces for bent pins, corrosion, or water intrusion
Verify battery voltage and good engine ground at the sensor connector
Perform a wiggle test on the harness while monitoring live data for intermittent changes

Typical position sensor signal: 0.5–4.5 V (0%–100% travel) — vehicle-specific values may vary
Alternate designs: open/closed (0 V/approx 5 V) or pulse-width/ frequency signal on some systems
Supply voltage to sensor: ~5 V reference (verify with back-probing)
Ground: near 0 V (check for low-resistance to chassis ground)
Resistance: if sensor is variable resistor type, expect manufacturer resistance chart — consult service data

Read and record freeze frame and live-data PIDs (bypass valve C position, engine coolant temp, sensor supply voltage)
Visually inspect the bypass valve, sensor, and wiring harness for obvious damage, corrosion, or fluid contamination
With ignition on (engine off), back-probe sensor connector: verify reference voltage present (typically ~5 V) and proper ground; if absent, trace power/ground to fuse/ECM
Measure sensor signal voltage while slowly moving/operating the valve (if accessible) or while commanding valve from scanner if supported — signal should change smoothly within expected range
Check continuity and resistance of wiring between sensor connector and ECM; repair any open or high-resistance circuits
Perform wiggle test on harness/connectors while monitoring live data to find intermittent faults
If wiring and power/ground are good but signal abnormal or stuck, remove and bench-test or replace the bypass valve/position sensor assembly
After repair, clear codes and perform test drive to confirm proper operation and that code does not return
If all wiring and sensor checks are good and the fault persists, consider ECM input circuit testing or ECM replacement as last resort (consult manufacturer procedures)