Powertrain, generic · Transmission

P0730 Incorrect Gear Ratio

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0730 reports a wrong transmission ratio without assigning it to a gear. Two uses are documented. Older Aisin-type automatics (a 2006 GM table, Saab's 9-5 of 2002) set it when fourth or fifth gear shows the ratio of third – a shift solenoid (Saab: S3) is not switching; GM lights the MIL at once, Saab enters limp mode. GM's continuously variable transmissions of 2023 and 2025 use it when the pulleys do not reach the commanded variator ratio – the belt or chain slips or clamping pressure is too low – after one trip. Ford and newer GM step automatics use gear-specific or clutch valve codes instead. Check fluid level and condition first.

Likely causes

Fluid level or quality (CVT fluid or ATF)
Shift solenoid or pressure control valve sticking or faulty
Clutch or brake wear, or worn variator belt, chain or pulleys
Faulty speed sensor signal

Symptoms

  • Slipping, engine speed rises without drive
  • Wrong gear or missing upper gears, limp mode
  • Check engine light (GM) or transmission warning
  • CVT: judder, weak acceleration

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–5,000
Time1–14 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Check fluid level and smell
  2. Read transmission module data
  3. Have the transmission inspected

Parts involved

transmission valve bodyshift solenoidcvt variatortransmission fluid

Related codes

P0731P0732P0733P0734P0735P0736

References: gsi.ext.gm.com, gsi.ext.gm.com, saabwisonline.com.