P0734 code meaning
Gear 4 Incorrect Ratio
Powertrain system Generic code P07xx codes Check engine light
What P0734 means
The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. Thresholds: Ford more than 30 rpm off for 1.8 s three times (diesel 2023: over 20 % for 12 s), GM's 2006 tables and the Allison 1000 converter slip of 200–230 rpm for 2.25 s after one trip, Saab's Aisin boxes over 20 % twelve times without MIL. P0734 concerns fourth gear. A 2006 GM table separates it explicitly from P0730: fourth gear showing the ratio of third is P0730, any other deviation P0734. Slip shows as raised engine speed or no upshift into fourth. On GM manual transmissions it checks the gear position sensor.
P0734 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 14 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0734
- Slipping or flare in fourth gear, engine speed higher than expected
- Harsh or delayed shifts
- Limp mode (Aisin: second gear and reverse only), transmission warning
- Check engine light depending on manufacturer
Common causes of P0734
- Most likelyFluid level too low or fluid worn or contaminated
- Most likelyClutch or brake for fourth gear worn (linings, piston seal)
- PossibleSticking shift or pressure valve, leaking valve body gasket, blocked passages
- PossibleGM manual transmissions only: gear position sensor faulty or not learned
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Transmission clutchesTransmission valve bodyTransmission fluidTransmission control module
What each part of P0734 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 34 | The exact fault in that area. |
What to do next
- Note P0734 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0734
What does P0734 mean?
P0734 means "Gear 4 Incorrect Ratio". The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. It is a generic code, so it means the same on every make.
Is it safe to drive with P0734?
Drive gently and only to a workshop. With P0734 the car can go into limp mode (reduced power) to protect itself.
Will P0734 fail an emissions test?
Yes, it can. P0734 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0734 to fix?
Difficulty: hard. A typical repair takes 0.5 to 14 hours of work. This is a job for a workshop.
Will P0734 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.