P0732: Gear 2 Incorrect Ratio

P0732 means the speed relationship between the input and output shafts, measured while second was commanded, did not match the value second is supposed to produce. Something between the engine and the wheels is not holding.

The most useful context for this particular gear is how often it is used. Every time the vehicle pulls away from a standstill it passes through second, which means the friction element that holds second accumulates apply cycles faster than any other element in the transmission. A car doing short urban journeys can shift into second several hundred times a day. Nothing else in the gearbox works that hard. So a second-gear ratio fault on a high-mileage city vehicle is not evidence of a weak design or a manufacturing problem — it is the element with the most cycles on it reaching the end of its service life first, exactly as you would predict. The same code on a vehicle that has spent its life on motorways is a much more surprising finding and deserves a harder look at fluid history and at whether the transmission has been overheated.

There is a second point specific to this gear that changes what the repair might be. On a good number of step-automatic designs, second gear is held not by a multi-plate clutch pack but by a band — a steel strap lined with friction material that wraps around a drum and is tightened by a hydraulic servo. Bands behave differently from clutches when they wear. They glaze, they stretch, and the servo that applies them can lose its seal. Critically, on a number of older and heavy-duty designs the band is externally adjustable through the transmission case, which makes a second-gear ratio complaint one of the very few internal transmission faults that can sometimes be corrected without splitting the unit. Whether your transmission has an adjustable band is worth thirty seconds in service data before anyone quotes a rebuild.

There is also a specific way to provoke this fault on a road test, and it runs against instinct. Line pressure rises with throttle opening, so a marginal friction element is best held by an aggressive shift and most likely to slip on a gentle one. Testing with hard acceleration masks the fault. Drive it with the fluid fully warm and make light-throttle shifts into second at low road speed, watching the ratio in live data. That is the condition where a worn element shows itself first, and doing it the other way round is why some of these come back reported as no fault found.

Second gear is also where several other functions live. Winter and snow modes start the vehicle in second to reduce wheelspin, and many strategies select second for engine braking on a descent. A driver who reports that the winter mode has stopped working, or that the vehicle no longer holds back on hills, may be describing this fault before the code has ever been read.