Reverse Incorrect Ratio

Possible causes

• CommonLow or badly degraded transmission fluid
• CommonWorn clutch pack or band for reverse
• CommonFailed or stuck shift solenoid for reverse
• CommonSticking valve in the valve body, so pressure never reaches the clutch
• PossibleLow line pressure - worn pump or failed pressure control solenoid
• PossibleFaulty speed sensor making a healthy gear look wrong
• PossibleInternal seal or drum failure

What you might notice

• Slipping - engine speed rises without matching acceleration
• Transmission not engaging reverse, or flaring on the way into it
• Harsh shifts
• Limp mode, holding one gear
• Burnt smell from the fluid

What to check, in order

1. Check the fluid level and condition first. Low or burnt fluid is the most common cause, and it is the only cause you can address cheaply.
2. Drive it and note what actually happens in reverse. Slipping under load points at the clutch pack; failing to engage at all points at a solenoid or valve body.
3. Read all stored codes. A solenoid code alongside this one names the likely cause; several ratio codes together point at low line pressure or fluid affecting the whole transmission.
4. Compare input and output speed on the live data screen and work out the actual ratio in reverse against the specification.
5. Look at the fluid on the dipstick or drain plug for clutch material - a dark grey, gritty film means internal wear.
6. Be realistic about cost before spending on parts. A single ratio code on an otherwise healthy transmission can be a solenoid; several of them with burnt fluid usually means a rebuild.