OBD-II trouble code
P0941: Hydraulic Oil Temperature Sensor Circuit Intermittent
The temperature signal drops out or jumps and then recovers. Reproducing it means working the clutch rather than idling the car, because this fluid is heated by the pump that drives it.
Quick facts
- System
- Powertrain
- Category
- Transmission
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $80 – $1,800
- DIY difficulty
- Shop recommended
Browse every code in P0900–P0999, or start from the full code library.
What does P0941 mean?
P0941 says the module has caught the hydraulic oil temperature signal misbehaving briefly and then returning to normal. Nothing is wrong when the car arrives at the workshop, which is the entire problem.
The first thing to establish is what the module actually judged, because it is not judging instantaneous values. High hydraulic oil temperature is a perfectly normal transient in this system. A run of hill starts, a few minutes of manoeuvring a trailer, or a long crawl in traffic on a gradient will all push the fluid up hard and fast, and the module expects it. What it faults is a value that is sustained beyond a physically plausible period, or a value that appears and vanishes faster than fluid temperature can actually change. A trace that jumps forty degrees between two samples has not measured a thermal event — fluid does not do that — so it has measured an electrical one. Distinguishing a physically possible excursion from an impossible one is most of the analysis, and it is done on the shape of the log rather than on any peak value.
The second thing is how to make the fault appear, and here the physics of the circuit point somewhere counter-intuitive. The heat in this fluid does not come from the engine. It comes from the actuator work itself and from the electric pump that pressurises the circuit, which is a resistive heat source sitting in the fluid it moves. That means hydraulic oil temperature is driven by how often the clutch and shift actuators are asked to do something, not by road speed or engine load. A car worked hard in a car park at walking pace will heat this fluid while engine coolant temperature is falling. So the road test that reproduces P0941 is not a motorway run — it is twenty minutes of repeated pull-aways, reversing and manoeuvring, with the scan tool logging. A technician who takes it out on a dual carriageway and reports no fault has tested the wrong thing.
As an electrical matter, intermittents in this location have a short list of causes, and they are dominated by mechanical disturbance rather than by component failure. Terminal tension that has relaxed, a connector that separates fractionally under vibration, a wire broken inside intact insulation that makes contact until the loom moves, a chafe that touches only at certain engine loads. Fluid contamination in the connector belongs on the list too and behaves differently — it tends to fail with temperature rather than with vibration, so a fault that correlates with a warm gearbox and not with rough road surfaces points that way.
The honest expectation to set with an owner is that this may take two visits. An intermittent that cannot be reproduced cannot be confirmed as fixed either, so the reasonable approach is to inspect and repair the most likely mechanical cause found, then re-drive and re-check rather than promise a cure on the first attempt.
Common causes
- Relaxed terminal tension in the sensor connector
- Wire broken inside intact insulation, making contact until the loom moves
- Harness chafe that touches only under certain engine loads or vibration
- Hydraulic fluid seeping into the connector and failing as it warms
- Connector not fully latched after previous work in the bell housing
- Thermistor failing intermittently at temperature
- Corrosion building on contact faces after a seal has aged
- Poor shared ground that opens only under electrical load
- Splice from an earlier harness repair breaking down under vibration
- Control module connector terminal issue at the transmission input pins
Symptoms
- Fault stored in history with nothing wrong on arrival
- Temperature reading jumping between values faster than fluid could change
- Occasional harsh or delayed engagement lasting a few seconds
- Check engine light that comes on and later clears itself
- Symptoms appearing during manoeuvring and parking rather than on the open road
- Fault more likely once the transmission is thoroughly warmed
- Brief unexplained appearance of a transmission warning message
- Adaptation values resetting or failing to settle over time
- Complaint that correlates with rough roads or speed bumps
- Fault recurring after a previous connector repair
Diagnostic steps
- 1.Read the freeze frame and note what the car was doing when the fault set, because the conditions are the most valuable clue an intermittent offers.
- 2.Log the temperature and look at the shape of the trace — a jump of tens of degrees between samples is electrical, since fluid cannot change that fast.
- 3.Road test by manoeuvring: repeated pull-aways, reversing and low-speed work for twenty minutes, which is what actually heats this fluid.
- 4.Do not rely on a motorway run, where the actuators do very little and the circuit stays cool.
- 5.Wiggle-test the harness and connector with live data displayed, working along the loom from the sensor towards the module.
- 6.Open the connector and check terminal tension individually rather than judging it by how the plug feels.
- 7.Look for hydraulic fluid inside the connector, which tends to cause failures that correlate with heat rather than with vibration.
- 8.Flex suspect harness sections to find a conductor broken inside undamaged insulation.
- 9.Check any previous repair splice in the loom, since a vibration-sensitive fault often traces back to earlier work.
- 10.After repair, repeat the manoeuvring road test rather than declaring success because the light stayed off on the drive back.
Repair cost
$80 – $1,800
Diagnosis is $80 to $250 and is usually the largest single line, because reproducing the fault takes road time rather than parts. A connector, terminal or harness repair is $110 to $360 and resolves the majority. A separately supplied hydraulic oil temperature sensor is $110 to $520 fitted. Where the sensor is part of the actuator or mechatronic assembly, $900 to $1,800. Budget for the possibility of a second visit: an intermittent that could not be reproduced cannot be confirmed cured either, and a workshop that promises otherwise is overpromising.
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DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.