P0940
WysokiCode P0940 indicates a high signal level in the hydraulic oil temperature sensor circuit. The control module (ECM/PCM/TCM) detects voltage higher than expected, which may indicate a sensor fault, short circuit, or wiring problem.
Code P0940 appears when the transmission controller detects excessively high voltage from the hydraulic oil temperature sensor. This can cause shifting problems and activate limp mode. The most common cause is a faulty sensor, a short circuit in the electrical system, or less often, a controller fault. Accurate electrical diagnostics will help avoid unnecessary replacement of expensive components.
Symptoms
Check Engine light illuminated (or transmission warning light), incorrect transmission operation (jerking, delayed shifts), possible hydraulic oil overheating, transmission limp mode, increased fuel consumption in automatic transmissions.
Possible causes
- Short circuit in the hydraulic oil temperature sensor circuit to positive voltage (e.g., damaged wire insulation) - Faulty hydraulic oil temperature sensor (internal short) - Damaged wiring (chafing, corrosion) - Faulty control module (ECM/PCM/TCM)
Affected systems
Does code P0940 require professional diagnostics?
The code alone is not enough. To find the cause, you need to read live data, check freeze frame conditions, and compare with vehicle behavior. Book a diagnostic session.