P0788 code meaning
Shift Timing Solenoid A High
Powertrain system Generic code P07xx codes Check engine light
What P0788 means
'Shift timing solenoid' means different parts: on GM's 4L60-E the 3-2 downshift solenoid that times the band apply on that downshift, on Aisin five-speeds (GM, Saab) the linear valve SLS that sets clutch pressure during the shift, and on the 2017–18 Genesis G80/G90 with shift-by-wire the on/off solenoids that engage drive (A) and reverse (B). P0788 means the circuit is shorted to positive or draws overcurrent. GM's 4L60-E checks the 3-2 downshift solenoid output for an invalid state at more than 43 of 50 counts; GM's Aisin-type five-speed flags SLS current above 1356 mA for 2 s and lights the MIL at once. Limp mode and shift jolts follow; the opposite is P0787.
P0788 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P0788
- Warning lamp
- Limp mode
- Shift jolts
Common causes of P0788
- Most likelyShort to positive in the harness
- PossibleWinding short in the solenoid
- Less likelyModule driver stage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Shift timing solenoidTransmission wiringTransmission control module
What each part of P0788 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 88 | The exact fault in that area. |
What to do next
- Note P0788 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 P0788
What does P0788 mean?
P0788 means "Shift Timing Solenoid A High". 'Shift timing solenoid' means different parts: on GM's 4L60-E the 3-2 downshift solenoid that times the band apply on that downshift, on Aisin five-speeds (GM, Saab) the linear valve SLS that sets clutch pressure during the shift, and on the 2017–18 Genesis G80/G90 with shift-by-wire the on/off solenoids that engage drive (A) and reverse (B). It is a generic code, so it means the same on every make.
Is it safe to drive with P0788?
Drive gently and only to a workshop. With P0788 the car can go into limp mode (reduced power) to protect itself.
Will P0788 fail an emissions test?
Yes, it can. P0788 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0788 to fix?
Difficulty: medium. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P0788 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.