Cause
Failed transmission speed sensor
A sensor reporting the rotational speed of an input, intermediate or output shaft inside the gearbox.
These sensors are the transmission's only way of knowing what gear it is actually in. Dividing input speed by output speed gives the ratio being delivered; comparing that against the ratio commanded tells the module whether the gear engaged and whether anything is slipping. Most performance and slip codes in the transmission range are derived from that arithmetic, so losing one signal disables far more than one measurement.
The commonest cause is not the sensor. It reads a toothed wheel through the fluid, and metal particles clinging to a magnetic tip will silence it while the sensor itself tests perfectly. Debris is something every transmission produces as it wears, and it collects on exactly the part that must stay clear.
After that, the internal harness. It runs in hot fluid and passes through a connector in the case wall, which is a known point for wicking and corrosion.
Expect limp mode. Without a believable ratio the module stops making shift decisions and locks a gear — which is protection, not further damage.
Typically specialist work. Needs equipment or training most home workshops do not have.
Codes this can cause (16)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0700 Transmission Control System (Malfunction Indicator Lamp Request) Likely for this code Moderate
- P2745 Intermediate Shaft Speed Sensor B Circuit Likely for this code Moderate
- P2746 Intermediate Shaft Speed Sensor B Circuit Range/Performance Likely for this code Moderate
- P2747 Intermediate Shaft Speed Sensor B Circuit No Signal Likely for this code High
- P2748 Intermediate Shaft Speed Sensor B Circuit Intermittent Likely for this code Moderate
- P2749 Intermediate Shaft Speed Sensor C Circuit Likely for this code Moderate
- P2750 Intermediate Shaft Speed Sensor C Circuit Range/Performance Likely for this code Moderate
- P2751 Intermediate Shaft Speed Sensor C Circuit No Signal Likely for this code High
- P2752 Intermediate Shaft Speed Sensor C Circuit Intermittent Likely for this code Moderate
- P2765 Input/Turbine Shaft Speed Sensor B Circuit Likely for this code Moderate
- P2766 Input/Turbine Shaft Speed Sensor B Circuit Range/Performance Likely for this code Moderate
- P2767 Input/Turbine Shaft Speed Sensor B Circuit No Signal Likely for this code High
- P2768 Input/Turbine Shaft Speed Sensor B Circuit Intermittent Likely for this code Moderate
- P2784 Input/Turbine Speed Sensor A/B Correlation Likely for this code Moderate
- U0402 Invalid Data Received From Transmission Control Module Likely for this code High
- P0C2F Internal Control Module Drive Motor/Generator - Engine Speed Sensor Performance High
Information, not instruction
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