P0938: Hydraulic Oil Temperature Sensor Range/Performance
What to do
Ask for this sensor to be compared against the other temperature readings on a fully cold car — that single comparison usually settles it without any further testing.
What this code means
The hydraulic fluid temperature reading is electrically valid but implausible — most often stuck at one value while the system plainly warms.
The cold-soak comparison used elsewhere in the corpus settles this in one reading: after the vehicle has stood overnight, every temperature sensor on it is measuring the same air, so coolant, intake, ambient and this one should agree within a few degrees. Whichever disagrees at that moment is the faulty one.
Likely causes
Start here
- Faulty hydraulic oil temperature sensor · moderate
Less common
- Hydraulic system leak · specialist
- Faulty hydraulic power unit · specialist
- Corroded transmission connector · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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