P0733 on Volvo: How to Diagnose & Fix
Gear 4 Incorrect Ratio
1 Volvo model · 1 documented issue · 1 critical · $900-$4,500 repair
P0733 on Volvo by model: symptoms, diagnosis and fix
P2-generation S60s use the Aisin-Warner AW55-50SN 5-speed automatic. Two related failures dominate owner reports: the transmission control module (TCM), which is mounted inside the transmission case and bathed in hot ATF, develops cracked solder joints and internal failures, and the transmission's clutch packs and valve body wear prematurely because Volvo originally specified the fluid as 'lifetime fill'. Symptoms usually begin as harsh or delayed 1-2 and 2-3 shifts, then progress to flare-ups, limp-home mode (locked in 3rd gear), and eventually loss of forward or reverse. Owners on CarComplaints report 'Transmission/TCU Failure' and 'Lost Forward And Reverse' on early cars, and NHTSA has 16+ automatic-transmission complaints on the 2001 alone.
Common Symptoms
- Harsh or delayed upshifts, especially 1-2 and 2-3
- Transmission stuck in one gear (limp-home mode)
- Loss of forward and reverse engagement
- Flaring / RPM surge between shifts
- Check engine light with transmission codes
- Burnt-smelling, dark transmission fluid
How to Fix
Diagnose first: many cars respond to a TCM software update plus a full drain-and-fill (not a flush) with Volvo JWS 3309 / Toyota T-IV fluid, repeated 2-3 times, and replacement of the transmission fluid filter and pan gasket. Volvo also issued updated shift-adaptation software for the AW55-50SN. If the TCM itself has failed, it can often be rebuilt/resoldered by a specialist far cheaper than a dealer unit, but the replacement module must be programmed to the car. Once clutch material is in the fluid or the car has lost drive, a rebuilt or remanufactured transmission with an updated valve body is the only durable fix. Preventively, change the fluid every 40-50k miles regardless of the 'lifetime' claim.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Aisin 1161540KT2 AW50/AW55 JWS 3309 transmission service kit
supply the exact JWS 3309 fluid branch for a diagnosed, still-serviceable AW55 transmission Fitment/availability: 2001-2009 Volvo S60 only after confirming the installed Aisin AW55-50SN/AW55-51 transmission; kit supplies one JWS 3309 dra…
- Genuine Volvo 1161540 JWS 3309 automatic transmission fluid, 1 liter
genuine-fluid alternative for the exact JWS 3309 specification named in How to Fix Fitment/availability: AW55-equipped 2001-2009 Volvo S60; order the quantity required for the planned drain-and-fill sequence and confirm transmission iden…
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Sources for this issue (2)
P0733 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 P0733 mean on a Volvo?
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 Volvo it is documented across 1 model: S60.
What are the most common causes of P0733?
The most common causes of P0733 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0733 on a Volvo?
Published repair estimates on Volvo range from $900 to $4,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0733 on a different make?
View P0733 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.