Crankshaft Position Sensor Signal Lost

Common Symptoms

• Engine cranks normally but will not fire and start
• Engine starts fine cold but stalls suddenly under mowing load
• Engine runs rough and cuts out at higher RPM
• Tachometer on the mower deck panel reads zero or fluctuates erratically while cranking
• Check engine light or fault indicator illuminates on equipped mower panels
• Engine may restart after cooling down but fault returns under load
• KDS scanner shows active P0335 code on EFI-equipped models

Probable Causes (Ranked by Likelihood)

• Crankshaft position sensor failed internally, no signal output Very Likely
• Damaged or broken wiring harness between sensor and ECU, often from heat or belt contact Very Likely
• Sensor air gap out of specification, sensor too far from trigger wheel Likely
• Trigger wheel on crankshaft damaged, missing teeth, or packed with debris Likely
• Corroded or loose connector at the sensor pig-tail or ECU harness plug Possible
• ECU power or ground circuit fault causing intermittent signal dropout Less Likely
• Failed ECU unable to process valid sensor signal Less Likely

Step-by-Step Diagnostic Procedure

1. Start by pulling the sensor connector and inspecting the pins. Look for corrosion, pushed-back terminals, or melted plastic. A green or white crust on the pins means moisture got in. Clean with electrical contact cleaner and a small pick before anything else.

2. Set your multimeter to DC volts. With the key ON and engine off, check for reference voltage at the sensor connector. On Kawasaki EFI engines the ECU supplies a 5V reference signal to the sensor. No voltage here means you have a wiring or ECU supply problem, not a bad sensor.

3. Switch your meter to resistance (ohms). Unplug the sensor and measure resistance across the sensor terminals. A healthy Kawasaki crankshaft position sensor typically reads between 200 and 1,000 ohms depending on the specific model. An open reading (OL) or near zero ohms means the sensor is internally failed and needs replacement.

4. Inspect the wiring harness from the sensor back toward the engine block and ECU. Run your fingers along the entire length looking for chafed insulation, pinched sections near the blower housing, or spots where the wire may have contacted a hot surface or moving belt. Any bare copper means you found your fault.

5. Check the sensor mounting and air gap. The sensor tip should sit close to the reluctor ring on the crankshaft without touching it. The spec for most Kawasaki FX and FS series EFI engines is 0.020 to 0.040 inch (0.5 to 1.0 mm). Use a feeler gauge. If the sensor has shifted or the bracket is bent, the gap may be too large for a reliable signal.

6. Remove the sensor and shine a light onto the trigger wheel (reluctor ring) on the crankshaft. Look for missing or bent teeth, and check that the wheel is free of packed grass clippings, mud, or debris that could block the sensor from reading each tooth pass.

7. If wiring, gap, trigger wheel, and connector all check out, connect a KDS diagnostic tool on EFI-equipped engines and watch live sensor data while cranking. No RPM signal while cranking confirms the sensor is not producing output. At that point replace the crankshaft position sensor. If a KDS tool is not available, a known-good replacement sensor is the next practical step.

8. After replacing the sensor or repairing the harness, clear the fault code with the KDS tool, start the engine, and run it under real mowing load for at least 10 minutes to confirm the code does not return before returning the machine to service.

Frequently Asked Questions