P2766 — Input turbine speed sensor signal is unreliable

The engine control module is detecting an inconsistent or impossible signal from the input or turbine speed sensor B. This sensor monitors the transmission's input shaft speed to help manage shifting and torque converter operation.

Common causes

The cause is almost always one of a few things. Here they are — P2766 rarely comes from anything outside this list:

• Faulty input/turbine speed sensor B
• Damaged or corroded wiring/connectors
• Transmission fluid contamination or low level
• Faulty transmission control module
• Internal transmission mechanical problems

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Inspect and clean sensor connectors and wiring
2. Check and top up transmission fluid if needed
3. Test sensor output and replace if faulty
4. Scan and reset transmission control module
5. Diagnose internal transmission if problems persist

That is what holds for P2766 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.