P0734 Gear 4 incorrect ratio
What P0734 means
The transmission control unit has found that the speed ratio in fourth gear is wrong. The clutch or band for fourth gear is probably slipping, often noticed at cruising speed.
P0734 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 500–4000 €
- Workshop time
- 4–16 h
- Repair difficulty
- Hard
- DIY possible
- No
- Check engine light
- Yes
- Affects emissions test
- No
- Limp mode possible
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Revs rising at steady cruising speed
- Harsh or delayed shift into 4th
- Gearbox holding a lower gear
- Limp mode
Common causes
- Low or degraded transmission fluid
- Worn fourth-gear clutch or band
- Faulty shift solenoid or valve body
- Low line pressure
Can I keep driving with P0734?
Have it checked within a day or two and avoid long motorway drives. A slipping gear can quickly destroy the gearbox.
What to check first
- Check fluid level and condition
- Check for solenoid or pressure codes
- Change fluid and filter if needed and retest
- Have pressure tests and an internal inspection done
Related codes
- P0733 Gear 3 incorrect ratio
- P0735 Gear 5 incorrect ratio
- P0732 Gear 2 incorrect ratio
- P0731 Gear 1 incorrect ratio
- P0730 Incorrect gear ratio
- P0740 Torque converter clutch circuit/open
- P0741 Torque converter clutch circuit performance/stuck off
- P0743 Torque converter clutch circuit electrical
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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