OBD-II code · Powertrain (generic)
P078B Shift Timing Solenoid B Range/Performance
Shift timing solenoid B is electrically intact, but actual shift timing does not match the model — same failure modes as solenoid A (aged, dirty ATF), applied to the second timing channel.
Is it safe to drive with P078B?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyAged solenoid with weakened force
- Less likelySensor element aged beyond calibration window
- Less likelySensor mounting loose - signal damping
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–8 h
- Emissions test
- Usually unaffected
- Parts involved
- Shift Timing Solenoid B, Transmission Fluid
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.