P07CB
- Powertrain
- Generic (SAE)
Diagnose soon
Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
Transmission Fluid Thermostat Performance
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
The transmission fluid thermostat (similar in function to a coolant thermostat — opens at a calibrated temperature to route ATF through the cooler) does not regulate temperature within the expected band. Either stuck open (ATF stays cold, friction modifier ineffective) or stuck closed (ATF overheats, oxidising the fluid).
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
- Urgency
- Diagnose soon
- Will it pass emissions
- Not affected
- Check engine light
- Solid
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Thermostat stuck open | Very common | — |
| 2 | Thermostat stuck closed | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Transmission Fluid Thermostat
- Transmission Cooler
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
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