Low or degraded automatic transmission fluid (ATF) level or condition; Worn or burnt third-gear clutch packs or bands; Sticking or faulty shift solenoid or valve body spool valve; Internal transmission hydraulic pressure loss due to worn seals or pump; Faulty input or output speed sensor providing inaccurate ratio data; Damaged wiring or connector at the transmission speed sensors; Mechanical failure inside the transmission such as a broken band or planetary gear set

DTC codes / P07xx · Transmission / P0733

P0733Gear 3 Incorrect Ratio

Q: What does code P0733 mean?

Gear 3 Incorrect Ratio. P0733 means the transmission control module (TCM) commanded third gear but the measured ratio between the input and output speed sensors did not match the programmed third-gear ratio. The computer detected a mismatch beyond its calibrated tolerance, which points to a slipping or incorrectly engaged third gear rather than an electrical fault in the sensor circuit itself.

P0733 means the transmission control module (TCM) commanded third gear but the measured ratio between the input and output speed sensors did not match the programmed third-gear ratio. The computer detected a mismatch beyond its calibrated tolerance, which points to a slipping or incorrectly engaged third gear rather than an electrical fault in the sensor circuit itself.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaTransmission

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) with no noticeable change in driveability
Harsh or delayed shifts, especially on the 2-3 or 3-4 shift
Transmission stuck in limp mode or limited to a single gear
Slipping or flaring during acceleration in third gear
Elevated engine speed without corresponding vehicle speed increase
Transmission may downshift abruptly or refuse to engage third gear

Common causes, most likely first

Low or degraded automatic transmission fluid (ATF) level or condition
Worn or burnt third-gear clutch packs or bands
Sticking or faulty shift solenoid or valve body spool valve
Internal transmission hydraulic pressure loss due to worn seals or pump
Faulty input or output speed sensor providing inaccurate ratio data
Damaged wiring or connector at the transmission speed sensors
Mechanical failure inside the transmission such as a broken band or planetary gear set

How to diagnose and fix it

Check and correct automatic transmission fluid level and condition according to the manufacturer's procedure
Perform a visual inspection of the transmission wiring harness and speed sensor connectors for damage or corrosion
Use a scan tool to compare input and output speed sensor readings during a test drive in third gear
Test the shift solenoid and valve body operation with bidirectional scan tool controls or a pressure gauge
Inspect the transmission pan for debris or clutch material, which indicates internal wear
Perform a transmission pressure test to confirm hydraulic integrity in third gear
If internal mechanical or hydraulic faults are confirmed, remove and rebuild or replace the transmission

What the ratio test really reveals

A P0733 can be set by a faulty speed sensor even when the transmission is mechanically sound, so always verify live sensor data before condemning the gearbox.
Many vehicles store P0733 alongside P0730 or P0731-P0734 when multiple gear ratios are out of range, which often points to a shared hydraulic or electrical issue rather than a single gear failure.
A low fluid level caused by a slow leak can trigger P0733 without any visible puddle, so check the fluid level and condition before assuming internal damage.
Some transmissions use a calculated ratio from the output speed sensor and engine speed rather than a dedicated input sensor, making an engine speed signal fault a hidden cause of this code.
After a repair, the TCM may require a relearn or adaptive reset procedure before the code stays cleared, and skipping this step can cause a repeat false setting.

Can I keep driving with P0733?

Driving with P0733 risks further transmission damage and unpredictable shifting, so limit driving to a short distance to a repair shop and avoid heavy acceleration or highway speeds.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.