P0938

Code

Generic P — Powertrain

Hydraulic Oil Temperature Sensor Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 47 RU: 26

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Scan for P0938 and any related codes; record freeze-frame and live data
Visually inspect sensor harness, connector, and routing for damage or corrosion
Backprobe sensor connector and measure reference voltage, signal voltage, and ground with key ON
Measure sensor resistance (if applicable) across defined terminal(s) and compare to expected range
Compare module-reported hydraulic oil temperature to an independent thermometer probe in the fluid (if accessible)
Perform wiggle test on harness while watching live data for intermittent changes

Reference supply typically 5 V (varies by design); signal expected within 0.1–4.9 V depending on temperature
Sensor may be NTC thermistor (resistance decreases with higher temperature) or voltage-output type
Typical resistance ranges can be wide (roughly hundreds of ohms to tens of kilohms depending on design) — consult vehicle data
Operating temperature detection range commonly -40°C to +150°C (varies by application)
Expected PCM/TCM hydraulic oil temperature reading should track an external thermometer within a reasonable tolerance (few degrees)

Retrieve codes and live data. Note freeze-frame conditions (engine load, speed, oil temp).
Visually inspect sensor and harness for damage, corrosion, pin push-out, or oil intrusion. Repair connectors as needed.
With ignition ON (engine OFF), backprobe connector: verify reference voltage present and good ground. If missing, trace wiring to module.
Measure sensor signal voltage and compare to expected voltage table for known temperatures. If vehicle documentation gives resistance vs temperature, heat/cool sensor and verify change.
If signal or resistance out of range, disconnect sensor and measure resistance directly at sensor terminals. If sensor fails known-good test, replace sensor.
If sensor tests good at connector but signal abnormal at module, perform continuity tests and check for short to power or ground in harness. Repair any wiring faults.
Verify hydraulic oil level and condition. If oil is severely contaminated or degraded, service fluid and retest sensor behavior.
After repairs or replacement, clear codes and perform functional test / road test while monitoring live data. Confirm code does not return.
If wiring and sensor verify good yet code persists, consider module diagnostics or replacement per manufacturer procedures.