P0734 on Chrysler: How to Diagnose & Fix
Gear 4 Incorrect Ratio
1 Chrysler model · 1 documented issue
P0734 on Chrysler by model: symptoms, diagnosis and fix
The ZF 9HP 9-speed automatic transmission in the Pacifica exhibits harsh or jerky 3-4 shifts, shuddering during light throttle acceleration at 25-40 mph, and occasional hesitation when downshifting. The 9-speed has had multiple software calibration updates since launch, and the adaptive learning can become confused by varied driving patterns. Cold weather worsens the harsh shifting. The issue persists across multiple model years despite ongoing TSBs.
Common Symptoms
- Harsh or jerky 3-4 upshift
- Shudder during light acceleration at 25-40 mph
- Hesitation or hunting between gears on hills
- Transmission feels rough when cold
- Occasional delayed downshift when passing
How to Fix
Visit a dealer for the latest transmission control module (TCM) software update — Stellantis has released numerous calibration updates (most recent as of 2025 is TSB 21-013-24 or newer). After the update, the transmission needs a re-adaptation period of 500-1,000 miles of mixed driving. If harsh shifting persists, a transmission fluid drain and refill with Mopar ZF 9-speed fluid may help. In severe cases, valve body replacement resolves persistent harsh shifts ($1,000-$2,000).
Find a Chrysler dealer
Choose to share your location for this search, or enter an area below. Your search location is sent to Google to find dealers.
Open Chrysler dealer map in Google Maps ↗Call to confirm they service Chrysler vehicles and check your VIN, recall eligibility, parts availability, and appointment options.
Sources for this issue (1)
P0734 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0734 mean on a Chrysler?
P0734 stands for "Gear 4 Incorrect Ratio." This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 4th gear. The module continuously compares input shaft speed to output shaft speed; if the ratio in 4th gear doesn't match the expected value, it sets P0734. This usually indicates the transmission is slipping or not fully engaging 4th gear due to a hydraulic, friction, or solenoid problem. Symptoms include slipping, flaring RPM, harsh or missed shifts, and possibly limp mode. On Chrysler it is documented across 1 model: Pacifica.
What are the most common causes of P0734?
The most common causes of P0734 are: Low or degraded/burnt transmission fluid, Slipping clutch packs or worn friction elements in 4th gear, Stuck or faulty shift solenoid, Valve body / internal hydraulic leak or restriction, Worn or failing torque converter, Faulty input or output speed sensor, Internal mechanical wear (bands, planetary gears). The specific cause varies by vehicle.
How much does it cost to fix P0734 on a Chrysler?
Repair costs vary widely with the root cause and Chrysler model; each issue on this page carries its own estimate where one is published.
Looking for P0734 on a different make?
View P0734 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.