P0935

Code

Generic P — Powertrain

Hydraulic Pressure Sensor Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 40 EN: 50 RU: 34

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Page language: EN

Causes

Faulty hydraulic pressure sensor (internal short or failed output)
Short to battery/ignition voltage on the sensor signal circuit
Poor connector connection, corroded terminals, or damaged wiring
Hydraulic pressure actually higher than expected due to stuck valve or mechanical fault
Incorrect sensor installed or wrong sensor calibration
PCM/ECM hardware failure or missing/incorrect reference voltage

Symptoms

MIL (Check Engine) illuminated
Transmission harsh shifting, delayed shifts, or stuck in limp/limitation mode
Erratic pressure readings in live data (very high values)
Reduced performance or inability to shift into higher gears
Possible transmission fault codes in addition to P0935

What to check

Read freeze frame and related/transmission codes, note conditions when code set
Visually inspect sensor connector and wiring for damage, corrosion, or pin push-out
Check transmission/hydraulic fluid level and condition (contamination, overfill)
Scan live data: monitor hydraulic pressure sensor signal while cranking and during drive
Backprobe sensor: verify reference voltage (usually ~5V) and ground present before testing signal
Perform wiggle test on wiring/connector while monitoring live data for intermittent changes

Signal parameters

Reference supply typically ~5.0 V (check OEM spec for vehicle-specific value)
Normal sensor signal usually varies within ~0.5–4.5 V depending on pressure (vehicle-specific)
Anomalous/high condition: signal above the upper expected voltage threshold or pegged near battery voltage
Resistance/open-circuit checks: sensor resistance values are vehicle-specific—consult service manual
Check for low impedance to battery (+12V) on the signal wire when the fault is present

Diagnostic algorithm

Retrieve and record all codes and freeze-frame data. Note operating conditions when P0935 set.
Visually inspect sensor, harness, and connector for damage, corrosion, or fluid intrusion. Repair any obvious issues.
Check hydraulic/transmission fluid level and condition; correct if necessary and clear code, then retest.
With ignition ON (engine off), backprobe connector: verify reference voltage and ground are within spec. If reference is missing or out of spec, trace and repair power/ground circuits.
Measure the sensor signal voltage with key ON and during engine run/gear changes. Compare to expected ranges in service manual. If signal is abnormally high (near battery voltage), suspect short to battery or sensor internal fault.
Inspect wiring continuity between sensor and PCM. Check for short to battery (+12V) and short to ground. Repair damaged wiring or connectors.
Perform wiggle/road test while monitoring live data to identify intermittent wiring faults.
If wiring and power/ground are good, substitute a known-good sensor (or bench test sensor if possible) and re-evaluate.
If a known-good sensor does not clear the issue and wiring checks OK, test PCM reference and inputs per manufacturer procedures; consider PCM diagnosis/repair.
After repair or part replacement, clear codes and perform a test drive to confirm the fault does not return and vehicle behavior is normal.

Likely causes

Damaged or contaminated sensor or connector
Wiring short to battery/ignition feed on the signal wire
Open or high-resistance ground or reference circuit to the sensor
Actual hydraulic system overpressure caused by valve/actuator fault
Intermittent PCM reference voltage or PCM fault (less common)

Fault status

⚠️ Status

Hydraulic Pressure Sensor Circuit High (P0935): PCM detected a sensor signal higher than allowed. This may set the MIL and cause transmission/hydraulic control abnormalities until the root cause (sensor, wiring, or actual overpressure) is corrected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours