P0732
Generic (SAE)
Gear 2 Incorrect Ratio
Severity
High
Typical repair cost
150 – 3 000 EUR
System
Powertrain
What it means
The TCM compares the measured input/output speed ratio with the theoretical 2nd gear ratio whenever 2nd is commanded. P0732 sets when the deviation exceeds the tolerance for a set time, indicating that the clutch or band responsible for 2nd is slipping or not applying. The code typically triggers limp mode with a fixed gear and maximum line pressure.
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Symptoms
- RPM flare during the 1-2 upshift, then a bang as it catches
- Slipping or shuddering in 2nd under moderate acceleration
- Transmission skips 2nd and goes 1-3, or holds 3rd/4th only
- Delayed downshift to 2nd when slowing for corners
- Overheating and dark fluid after city driving
Common causes
- Worn 2nd gear brake band or clutch pack friction material
- Band servo piston seal leaking or servo apply pin worn (band-type transmissions)
- Sticking 1-2 shift valve or worn valve body bore
- Faulty shift solenoid B or pressure control solenoid for the 2nd gear circuit
- Low fluid level or degraded fluid
- Cracked accumulator piston or weak accumulator spring
How to diagnose
- Verify fluid level and condition at operating temperature; correct before testing.
- Road test while recording input speed, output speed and commanded gear; in 2nd the ratio should match spec (e.g. 2.34:1) within 5 %. A ratio drifting toward the 1st gear value means 2nd is not applying; a ratio above spec with rising input RPM means slip.
- Use the scan tool to check solenoid commands and the TCM's slip counter or adaptation values for 2nd gear; maxed-out adaptation indicates mechanical wear.
- Measure shift solenoid B resistance (typically 10-25 ohms, or 3-8 ohms for linear types) and compare with the other solenoids; swap with an identical solenoid if the design allows and see if the fault moves.
- Check line pressure in Manual 2 at idle and at 2500 rpm; a drop of more than 1 bar compared with Drive points to a leak in the 2nd gear apply circuit (servo, sealing rings).
- Inspect the pan: fibrous debris confirms band/clutch wear; remove the valve body for inspection or exchange, otherwise plan an overhaul.
Frequently asked questions
Can I keep driving in limp mode?
For a short distance at low speed, yes. Prolonged driving in a fixed gear overheats the fluid and spreads clutch debris through the hydraulics, raising the repair bill.
Is P0732 always mechanical?
No. A sticking solenoid or dirty valve body can produce the same ratio error. A clean pan and good pressure readings favour a hydraulic control fault that is much cheaper to fix.