What does it mean?
P1356 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 1 Ignition Circuit Short to B+ .
Symptoms
- Cylinder 1 misfires or does not fire at all, giving a rough, shaking idle
- Check engine light on, often flashing while the misfire is present
- Poor acceleration and reduced overall power
- Fuel smell from the exhaust and higher fuel consumption
- Possible extra misfire codes for the same cylinder stored alongside
Likely causes
- Control wire touching a permanently powered circuit through damaged insulation
- Water in the coil connector bridging the control pin to the supply pin
- Internal short inside the coil between the feed and the primary control side
- Wire pinched against a powered terminal or bolt during earlier work on the engine
- Corroded connector where deposits form a conductive path between adjacent pins
- Incorrect repair splice connecting the control line to a switched power feed
- Damaged module driver already affected by the overvoltage condition
How to fix it
- Disconnect the coil for cylinder 1 and check the control wire for battery voltage with the key on; voltage there proves the short
- Inspect the connector for moisture, corrosion and pin-to-pin deposits, drying and cleaning it thoroughly
- Measure resistance between the coil control terminal and the supply terminal at the coil to detect an internal short
- Follow the harness from the coil toward the module looking for pinched, melted or repaired sections
- Check any previous splices or aftermarket wiring in that circuit
- Repair the short before installing new components, so a replacement coil or module is not damaged
- Replace the coil if the internal short is confirmed, then verify normal switching on the control line