What Does P1346 Mean?
P1346 indicates that the ignition coil power output stage 3 has a short circuit to battery positive (B+). The driver transistor circuit controlling coil 3 is experiencing an unwanted voltage supply on the control line, preventing proper switching. This creates a dead misfire on the cylinder driven by coil 3 and risks overheating the coil from sustained current flow.
Safety Warning
A coil short to B+ creates a fire hazard from overheating and causes a complete cylinder misfire. The ECU output stage may also sustain damage from reverse current flow. Immediate repair is recommended.
Common Causes
30%
Wiring harness damage causing coil 3 control wire to short to a power circuit
28%
Ignition coil 3 internal failure with short between B+ and control terminals
18%
Connector damage or contamination at coil 3 creating a bridge to B+
14%
ECU output stage 3 driver transistor failure
10%
Harness routing error after recent engine work placing control wire against B+ source
Diagnostic Steps
1
Disconnect ignition coil 3 and check for battery voltage on the control pin at the harness side with key on engine off. Voltage present indicates a harness or ECU issue.
2
Disconnect the ECU connector and recheck voltage on the coil 3 control wire. If still present, there is a harness short to B+ that must be traced and repaired.
3
Inspect the coil 3 harness for chafing, melted insulation, or contact with power feed wires, especially near the alternator, fuse box, or battery cables.
4
Test ignition coil 3 for internal short between the B+ power terminal and the control/signal terminal.
5
Check the coil connector for debris, corrosion, or deformed terminals that could bridge across pins.
6
After repair, verify proper coil 3 operation with an ignition scope pattern test and confirm no misfire codes return.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
P1346 indicates that the ignition coil power output stage 3 has a short circuit to battery positive (B+). The driver transistor circuit controlling coil 3 is experiencing an unwanted voltage supply on the control line, preventing proper switching. This creates a dead misfire on the cylinder driven b...
The most common cause of P1346 (Ignition Coil Power Output Stage 3 Short to B+) is: Wiring harness damage causing coil 3 control wire to short to a power circuit
Typical repair costs for P1346 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A coil short to B+ creates a fire hazard from overheating and causes a complete cylinder misfire. The ECU output stage may also sustain damage from reverse current flow. Immediate repair is recommended.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1346 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Manufacturer
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