P078E
Shift Timing Solenoid B Intermittent
Transmission
Generic OBD-II
Medium
What it means
P078E means the transmission control module saw an intermittent electrical fault in the shift timing solenoid B circuit, which helps control when a gear change is commanded. Because the fault comes and goes, you'll notice occasional mistimed or harsh shifts rather than a constant problem. It won't stop the engine from starting; the priority is tracing the intermittent wiring or solenoid fault before it turns permanent.
Medium
Can I keep driving? Shifts may occasionally be mistimed or harsh; the car is drivable, but have it checked before the fault becomes constant.
Common symptoms
What you'll notice
- Occasional rough or harsh shifting
- Inconsistent shift timing
- Check-engine light on (may come and go)
Common causes
Most likely first
- Intermittent wiring or connector fault in the shift timing solenoid B circuitLikely
- Faulty shift timing solenoid BCommon
- Low or dirty transmission fluidCommon
- Transmission control module (TCM) faultLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to capture the conditions when it set.
- Wiggle-test the solenoid B wiring and connector to reproduce the dropout.
- Check transmission fluid level and condition.
- Test the shift timing solenoid B resistance and operation.
- If wiring and solenoid are good, suspect the TCM. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P078E?+
Generally yes, for now. The fault is intermittent, so shifts are only occasionally rough. Repair it before it becomes a steady fault or forces limp mode.
Can I just clear P078E?+
Clearing hides it briefly, but an intermittent circuit fault will reset the code. Find the loose or damaged wiring, connector, or solenoid causing the dropout.
Related codes
Often seen with P078E
Read & clear P078E yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX