What does it mean?
P1810 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Input/Turbine Speed Sensor Circuit Malfunction Upper Threshold .
Symptoms
- Check engine lamp on, with a transmission warning or gear position message on some clusters
- Harsh, late or erratic upshifts, with rpm flare between gears
- Torque converter clutch refuses to apply, so engine speed stays high at steady cruise
- The transmission drops into limp mode and holds a single gear
- Rising fuel consumption and noticeably poorer drivability
Likely causes
- Signal wire touching a voltage source where the transmission loom passes a bracket, heat shield or the case connector
- Corroded, spread or backed-out terminals at the speed sensor connector, often after fluid has wicked into the connector body
- Metal debris collected on the sensor tip, or a chipped tone ring producing extra pulses
- Sensor internal circuit breaking down when hot and sending noise instead of a clean square wave
- Weak or corroded module ground raising the reference level of the whole circuit
- Damaged input circuit inside the module, usually after a short has been left uncorrected
How to fix it
- Read every stored code and the freeze frame; note the fluid temperature and gear at which the fault set
- Confirm the exact definition and pinout for the vehicle at hand, since manufacturer-specific codes in this range differ between brands
- Unplug the speed sensor connector and inspect for fluid, corrosion, spread terminals and a broken lock tab
- Graph input speed against engine rpm and output speed on a road test; a spike far above engine rpm proves the signal is false
- Check the signal wire for a short to battery voltage and measure the sensor resistance or output against specification
- Inspect the sensor tip and tone ring for debris and damage, and verify the mounting depth
- Replace the sensor only after the wiring is proven, then clear codes and re-drive the same conditions