What Does P1377 Mean?
The ignition circuit for cylinder 8 has a short circuit to battery positive voltage (B+). This creates an unsafe electrical condition and prevents proper ignition coil operation.
Safety Warning
Short to power can cause electrical fires, damage the ECM, and create serious safety hazards. Do not operate the vehicle until repaired.
Common Causes
40%
Damaged wiring harness with insulation worn through contacting power source
30%
Internally shorted ignition coil allowing voltage feedback
15%
Pinched or crushed wires near engine components or sharp edges
10%
Corroded connector terminals creating cross-circuit contact
5%
Aftermarket electrical work causing improper wire routing
Diagnostic Steps
1
Step 1: Disconnect cylinder 8 ignition coil and measure resistance to B+ on the control wire (should be infinite)
2
Step 2: Visually inspect entire wiring harness for melted insulation, burn marks, or damage
3
Step 3: Check for voltage on the coil control wire with ignition on and coil disconnected (should be 0V)
4
Step 4: Trace wiring from ECM to coil, checking for pinch points and contact with hot or powered components
5
Step 5: If wiring is intact, test ignition coil internal resistance and replace if shorted
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
The ignition circuit for cylinder 8 has a short circuit to battery positive voltage (B+). This creates an unsafe electrical condition and prevents proper ignition coil operation.
The most common cause of P1377 (Cyl. 8, ignition circuit Short Circuit to B+) is: Damaged wiring harness with insulation worn through contacting power source
Typical repair costs for P1377 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Short to power can cause electrical fires, damage the ECM, and create serious safety hazards. Do not operate the vehicle until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1377 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
