SPN 168 — Battery Potential / Power Input 1
System: Electrical
Voltage the engine computer sees on its main power supply.
Can I keep running it?
MEDIUM — fix soon
Low or unstable voltage can cause many unrelated codes and no-starts. Fix power first.
Likely causes
- Weak batteries
- Loose or corroded battery cables
- Charging system fault (alternator)
- Bad ECM power or ground connection
Checks & fixes (easiest first)
- Load-test batteries
- Clean and tighten battery and ground cables
- Check charging voltage at the alternator and at the ECM
- Voltage-drop test the ECM power and ground circuits
Common FMIs with SPN 168
- SPN 168 FMI 0Value too high (most severe)
- SPN 168 FMI 1Value too low (most severe)
- SPN 168 FMI 2Data erratic, intermittent, or incorrect
- SPN 168 FMI 15Value too high (least severe)
- SPN 168 FMI 17Value too low (least severe)
- SPN 168 FMI 18Value too low (moderately severe)
Related codes
FAQ
What does SPN 168 mean?
SPN 168 is Battery Potential / Power Input 1. Voltage the engine computer sees on its main power supply.
Can I keep running with SPN 168?
Low or unstable voltage can cause many unrelated codes and no-starts. Fix power first.
What causes SPN 168?
Weak batteries; Loose or corroded battery cables; Charging system fault (alternator); Bad ECM power or ground connection.