Cylinder 1 Injector Circuit Open or Shorted

Common Symptoms

• Engine runs rough or misfires noticeably, especially at low throttle
• Engine starts but immediately stumbles or lopes unevenly
• Power output feels like roughly half of normal, consistent with one cylinder not firing
• Fuel smell from exhaust because unburned fuel passes through the dead cylinder
• Check engine light or fault indicator illuminates on the mower's instrument panel
• RPM drops and engine surges under load on slopes or thick grass
• Kawasaki diagnostic tool (KDS) pulls active DTC P0201 from the ECU

Probable Causes (Ranked by Likelihood)

• Failed or shorted fuel injector on cylinder 1 internaly Very Likely
• Broken, chafed, or pinched injector wiring harness on cylinder 1 side Very Likely
• Corroded or loose connector at the cylinder 1 injector plug Likely
• ECU driver circuit failure -- ECU output for injector 1 has failed internally Possible
• Injector power supply fuse blown or relay contact failed Possible
• Water or debris intrusion into the injector connector causing a short to ground Less Likely

Step-by-Step Diagnostic Procedure

1. Step 1 -- Read the code with the Kawasaki diagnostic tool (KDS) if available. Confirm P0201 is active and not a stored ghost code from a previous event. Clear it, restart, and see if it returns immediately.

2. Step 2 -- Locate the cylinder 1 injector. On FX V-twin engines, cylinder 1 is typically the right-hand cylinder when viewed from the flywheel end. Visually inspect the wiring harness from the ECU to the injector for obvious chafing, melted insulation, or pinch points against the block or valve cover.

3. Step 3 -- Unplug the cylinder 1 injector connector. Inspect the terminals for corrosion, green oxidation, pushed-back pins, or moisture. Clean the connector with electrical contact cleaner and reconnect. Clear the code and test.

4. Step 4 -- With the injector disconnected and the key OFF, measure injector resistance across the two injector terminals using a multimeter set to ohms. Kawasaki EFI injectors typically read 12 to 16 ohms at room temperature. A reading near 0 ohms means a shorted injector coil. An open line (OL or infinite) means the injector coil is open. Either reading means the injector needs replacement.

5. Step 5 -- If injector resistance is within spec, check for continuity and shorts in the wiring harness. With the ECU connector unplugged and the injector unplugged, check continuity from the ECU pin for injector 1 signal to the injector connector pin. Then check for a short to ground on that same wire. Any short to ground or open wire means the harness needs repair.

6. Step 6 -- Verify injector supply voltage. With the ignition ON and the injector connector plugged in, use a multimeter set to DC voltage and backprobe the power supply terminal at the injector connector. You should see battery voltage (around 12V DC) on one terminal with the key ON. No voltage here points to a blown fuse, failed relay, or open power wire.

7. Step 7 -- If wiring and injector resistance both check out and the code still returns, the ECU driver for cylinder 1 may have failed internally. Swapping the cylinder 1 and cylinder 2 injector connectors is a quick field test. If the fault moves to P0202, the injector is fine and the ECU is suspect. This step requires a dealer or shop with ECU reprogramming capability for the replacement unit.

8. Step 8 -- If you are not comfortable probing ECU connectors or the fault points to the ECU, stop here and take the mower to a Kawasaki-authorized OPE service shop. ECU replacement on EFI FX engines requires programming with the Kawasaki diagnostic tool (KDS).

Frequently Asked Questions