P078AShift Timing Solenoid B
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- '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). P078A is the general circuit code for solenoid B. The only documented user is Hyundai/Genesis: on the 2017–18 G80/G90 with shift-by-wire it is the on/off solenoid that engages reverse. The bulletins replace valve and electronic module, then the transmission module if the code returns. Reverse may not engage, with warning lamp and limp mode.
- What you may notice
- Warning lamp
- Reverse cannot be engaged (Genesis shift-by-wire)
- Limp mode
- Likely causes
- LikelySolenoid faulty
- PossibleElectronic module or transmission module
- RareConnector or wire
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €200 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.