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
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