Gear 3 Incorrect Ratio

What it means

The transmission computer compares input and output shaft speeds. In gear 3, the ratio is not what it should be, which usually means a clutch pack or band is slipping.

Symptoms

• Transmission slipping (engine revs rise without the car speeding up)
• Harsh or delayed shifts
• Limp mode stuck in one gear
• Check engine or transmission warning light

Probable causes

Most likely first

1. 1Low or degraded transmission fluid
2. 2Worn clutch packs or bands
3. 3Faulty shift solenoid or valve body
4. 4Clogged transmission filter
5. 5Faulty input or output speed sensor

How to diagnose it

Work through these in order before buying parts

1. 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
2. 2Check the transmission fluid level and condition first (follow the maker's procedure; many need the engine running and the fluid hot). Dark, burnt-smelling fluid or metal debris points to internal wear.
3. 3Check speed sensor readings on live data.
4. 4Check for shift solenoid codes.
5. 5A transmission specialist may do a pressure test.
6. 6Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

• Fluid and filter service if the fluid is low or old (not a cure for worn clutches)
• Replace faulty solenoids or the valve body
• Rebuild or replace the transmission