P2788 code meaning
Auto Shift Manual Adaptive Learning at Limit
What P2788 means
P2788 is the system-level code for an automated manual gearbox whose learned correction values have reached the end of their allowed range. Such units learn the clutch bite point, engagement speed and the end stops of the shift and select movements so that gear changes stay smooth as parts wear; when a value would have to move beyond its limit, the controller can no longer compensate and stores this code. No manufacturer documents P2788 publicly; it falls under the comprehensive component rules of CARB 13 CCR 1968.2. Allison's bulletins on the related P2789 show the usual route: check whether engine torque data are plausible and whether newer software exists before replacing parts. Also check clutch wear, actuator travel and whether a relearn was skipped after repair. P2789 and P278F are the clutch-specific versions.
P2788 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P2788
- Jerky take-off and harsh or slow shifts
- Transmission warning lamp
- Clutch slip or engine flare during shifts
Common causes of P2788
- Most likelyWorn clutch moving the bite point beyond the learnable range
- PossibleBasic setting or relearn skipped after clutch, actuator or module work
- PossibleWorn or sticking shift and clutch actuators changing their travel
- Less likelyOutdated software or implausible engine torque signal
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
TCMClutch
What each part of P2788 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 88 | The exact fault in that area. |
What to do next
- Note P2788 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2788
What does P2788 mean?
P2788 means "Auto Shift Manual Adaptive Learning at Limit". P2788 is the system-level code for an automated manual gearbox whose learned correction values have reached the end of their allowed range. It is a generic code, so it means the same on every make.
Is it safe to drive with P2788?
Drive gently and only to a workshop. With P2788 the car can go into limp mode (reduced power) to protect itself.
Will P2788 fail an emissions test?
P2788 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P2788 to fix?
Difficulty: hard. A typical repair takes 0.5 to 6 hours of work. This is a job for a workshop.
Will P2788 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.