P0733 on Infiniti: How to Diagnose & Fix
Gear 4 Incorrect Ratio
1 Infiniti model · 1 documented issue
On Infiniti vehicles, P0733 (gear 4 incorrect ratio) is most often reported on the 2009-2013 Infiniti G37 as 7-Speed Automatic (RE7R01A) Harsh 2-1 Downshift, Gear Hunting and Ratio DTCs Requiring TCM/ECM Reflash ($0-$250 repair). Have an Infiniti dealer apply the latest TCM/ECM reprogram (bulletin family ITB10-075 / ITB12-027 and later revisions) with CONSULT-III; many owners report the harsh 2-1 downshift and hunting are cured or greatly reduced. If ratio codes persist after the reflash, the dealer flow is to inspect fluid level/condition and replace the valve body or torque converter. Each section below gives the symptoms, how to confirm the cause, the fix, parts and sources for that model.
Common causes of P0733 (all vehicles)
- Low or contaminated transmission fluid
- Worn 4th-gear clutch packs or bands
- Failing shift solenoid for 4th gear
- Valve body or line pressure issues
- Internal transmission mechanical wear
- Restricted transmission filter
- Faulty input or output speed sensor
P0733 on Infiniti by model: symptoms, diagnosis and fix
The 7-speed automatic introduced for the 2009 G37 developed a widely reported drivability complaint: a hard clunk on the 2nd-to-1st downshift when coasting to a stop, gear hunting/searching under light throttle, delayed or harsh upshifts when cold, and in some cases stored incorrect-gear-ratio codes. The MyG37 '7-speed transmission reprogram' thread runs well past 170 pages of owner reports. Infiniti responded with a series of TCM/ECM reprogramming bulletins (owners cite ITB10-075 and later ITB12-027 revisions) rather than hardware replacement; only a minority of cars needed a torque converter or valve body.
Common Symptoms
- Hard clunk or jerk on the 2-1 downshift when stopping
- Transmission hunts between gears at light throttle
- Delayed or harsh shifts when cold
- Check engine light with gear-ratio codes
How to Fix
Have an Infiniti dealer apply the latest TCM/ECM reprogram (bulletin family ITB10-075 / ITB12-027 and later revisions) with CONSULT-III; many owners report the harsh 2-1 downshift and hunting are cured or greatly reduced. If ratio codes persist after the reflash, the dealer flow is to inspect fluid level/condition and replace the valve body or torque converter. No recall; reflash was covered under powertrain warranty and is a nominal-cost labor item out of warranty.
Looking for P0733 on a different make?
View P0733 across all makes →Frequently asked questions
What does P0733 mean on a Infiniti?
P0733 stands for "Gear 4 Incorrect Ratio." This code indicates the transmission control module found that the actual gear ratio in 4th gear is outside the acceptable range for that gear. It is detected by comparing transmission input speed against output speed while 4th gear is engaged. A mismatch typically signals the transmission is slipping in 4th gear or that a control/hydraulic fault is preventing proper engagement. On Infiniti it is documented across 1 model: G37.
How do I diagnose P0733 on a Infiniti G37?
Have an Infiniti dealer apply the latest TCM/ECM reprogram (bulletin family ITB10-075 / ITB12-027 and later revisions) with CONSULT-III; many owners report the harsh 2-1 downshift and hunting are cured or greatly reduced. If ratio codes persist after the reflash, the dealer flow is to inspect fluid level/condition and replace the valve body or torque converter. No recall; reflash was covered under powertrain warranty and is a nominal-cost labor item out of warranty. Published repair guidance and available estimates are in the G37 section on this page.
What causes P0733 on Infiniti vehicles?
Documented causes on Infiniti: 7-Speed Automatic (RE7R01A) Harsh 2-1 Downshift, Gear Hunting and Ratio DTCs Requiring TCM/ECM Reflash. Generic causes of P0733: Low or contaminated transmission fluid, Worn 4th-gear clutch packs or bands, Failing shift solenoid for 4th gear, Valve body or line pressure issues.
How much does it cost to fix P0733 on a Infiniti?
Repair costs vary widely with the root cause and Infiniti model; each issue on this page carries its own estimate where one is published.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.