P0978
Shift Solenoid C Control Circuit Range/Performance
Transmission
Generic OBD-II
Medium
What it means
P0978 means shift solenoid C's control circuit isn't responding the way the transmission control module expects — the current or response is out of range. Shift solenoids route hydraulic pressure to engage gears, so this often shows up as erratic or delayed shifting. It's commonly a failing solenoid, a wiring fault, or low system voltage.
Medium
Can I keep driving? Usually drivable, but expect harsh or wrong-gear shifts and possible limp mode; repair it promptly to avoid extra wear.
Common symptoms
What you'll notice
- Check-engine light on
- Improper, erratic, or delayed gear changes
- Slipping or inability to engage certain gears
- Possible limp / failsafe mode
Common causes
Most likely first
- Faulty shift solenoid CLikely
- Wiring or connector problems in the solenoid circuitCommon
- Low system/battery voltage affecting the circuitCommon
- Failed transmission control module (TCM)Less often
- Internal transmission mechanical wearLess often
How to diagnose & fix
Work through it in order
- Scan freeze-frame and note the shift conditions when the code set.
- Confirm battery and charging-system voltage are within spec first.
- Inspect the solenoid wiring and connector for damage, looseness, or corrosion.
- Measure the solenoid's resistance against spec and test its operation with a scan tool.
- Replace the shift solenoid if faulty; if the circuit is good, investigate the TCM or internal wear. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0978?+
For short distances, yes, but the transmission may shift roughly or enter limp mode. Prolonged driving with slipping accelerates internal wear.
Can I just clear P0978?+
It returns until the solenoid, wiring, or low-voltage cause is fixed. Clearing only resets the light temporarily.
Related codes
Often seen with P0978
Read & clear P0978 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