Gear 4 Incorrect Ratio
What it means
P0734 means the transmission calculated the wrong gear ratio in 4th gear — the input and output shaft speeds don't match what 4th should be, which usually indicates slipping. Common causes are low or worn-out fluid, worn clutches, or a shift-solenoid/valve-body fault. It is a transmission fault, not an engine no-start; but continued slipping builds heat and wear, so it should be addressed promptly.
Can I keep driving? The transmission may slip in 4th, rev without gaining speed, or drop into limp mode — driveable gently, but continued slipping causes heat and wear, so fix it soon.
Common symptoms
What you'll notice
- Check-engine light on (sometimes a transmission warning light)
- Slipping in 4th gear — engine revs climb but speed doesn't follow
- Harsh or failed shift into 4th, or falling back out of it
- Limp mode and, over time, transmission overheating
Common causes
Most likely first
- Low or degraded transmission fluidLikely
- Worn clutches or bands slipping under loadCommon
- Faulty shift solenoid or a valve-body faultCommon
- Speed-sensor signal error, or less commonly a failed torque converter or TCMLess often
How to diagnose & fix
Work through it in order
- Scan and record freeze-frame data, and compare input vs. output speed to confirm the ratio error is in 4th gear.
- Check the transmission fluid level and condition first — low or burnt fluid is a common and cheap cause.
- Test the shift solenoids and inspect the valve body for sticking or a stuck valve.
- If fluid, solenoids, and sensors are good, the internal clutches or torque converter are likely worn and need a transmission specialist.
FAQ
Quick answers
Is it safe to drive with P0734?+
Can I just clear P0734?+
Related codes
Often seen with P0734
Read & clear P0734 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.