Incorrect Gear Ratio

Incorrect Gear Ratio

Modern vehicles equipped with automatic transmissions / transaxles use a torque converter between the engine and transmission to increase the engine torque output and drive the rear wheels.

This code can show up in vehicles with an automatic transmission when there is a problem shifting into or driving into any gear, this code is generic and does not specifically point to any particular gear ratio failure. The computer controlled automatic transmission uses multiple gear ratio's to increase vehicle speed while maximizing the power output from the engine. Newer vehicles may have more than four gear ratios to improve fuel economy. The computer determines when to shift up or down between gears based on throttle position vs. vehicle speed.

The Engine Control Module (ECM), Powertrain Control Module (PCM) or Transmission Control Module (TCM) uses input from various sensors to verify the correct operation of the transmission and its components. Engine speed is often calculated against the transmission speed sensor to determine gear ratio and torque converter slip. If the calculation does not match the desired value, the Diagnostic Trouble Code is set and the Check Engine Lamp is illuminated. Incorrect ratio codes typically require an advanced mechanical ability and diagnostic tools.

Note: This code is similar to P0729, P0731, P0732, P0733, P0734, P0735 and P0736. If there are other transmission codes, repair those problems first before proceeding with an incorrect gear ratio code.