Crankshaft Position Sensor Signal Lost or Missing
The BRIGGS-VANGUARD-P0335 (Briggs Vanguard) diesel fault code means: Crankshaft Position Sensor Signal Lost or Missing. This is a serious severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- moderate
- Estimated cost
- DIY sensor replacement: $40-$90 for the sensor plus gasket. Professional diagnosis and repair: $120-$280 depending on whether the fault is the sensor, wiring, or a reluctor ring issue requiring flywheel removal.
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Common Symptoms
- Engine cranks but will not fire and start
- Engine starts cold but stalls abruptly under load or at operating temperature
- EFI fault indicator light illuminates on equipped mower dash
- Engine RPM drops suddenly and engine shuts down without warning
- Vanguard EFI diagnostic tool shows active P0335 DTC
- Engine cranks normally but spark and fuel injection do not fire
- Intermittent stalling that gets worse as engine warms up
Probable Causes (Ranked by Likelihood)
- Crankshaft position sensor failed internally -- open or shorted winding Very Likely
- Sensor air gap out of spec due to debris buildup or sensor mounting shift Likely
- Damaged or chafed wiring harness between sensor and ECM -- connector pins corroded or backed out Likely
- Reluctor ring (tone wheel) on crankshaft damaged, cracked, or missing teeth Possible
- ECM connector contamination causing intermittent signal dropout Possible
- ECM internal fault causing loss of crank signal input circuit Less Likely
Step-by-Step Diagnostic Procedure
Start by connecting the Vanguard EFI diagnostic tool to confirm P0335 is active and check for any additional DTCs stored alongside it. Note whether the fault is active or pending, since an intermittent fault points toward wiring or air gap rather than a dead sensor.
Locate the crankshaft position sensor on the engine block near the flywheel. Visually inspect the sensor body for cracks, oil soaking, or impact damage. Inspect the 2- or 3-wire connector for bent pins, corrosion, or moisture intrusion.
Unplug the sensor connector and measure sensor resistance across the signal terminals with a multimeter. A healthy Vanguard EFI crank sensor typically reads between 500 and 1500 ohms. An open reading (OL) or a reading under 100 ohms indicates a failed sensor.
With the connector still unplugged, inspect the wiring harness back toward the ECM for any chafing against sheet metal, heat damage near the exhaust, or zip-tie pinch points. Repair any damaged insulation before replacing the sensor.
Check the sensor air gap using a feeler gauge. The sensor tip should sit 0.020 to 0.040 inch (0.5 to 1.0 mm) from the reluctor ring. If the gap is outside this range, loosen the sensor mounting bolt and reposition it. Torque the bolt to spec (typically 70-90 in-lb) after adjustment.
Inspect the reluctor ring teeth on the flywheel for damage. Rotate the flywheel slowly by hand and look for bent, cracked, or missing teeth. A damaged reluctor ring requires flywheel removal and is an advanced repair -- stop here and contact an authorized Briggs Vanguard service shop if you see ring damage.
After any sensor replacement or harness repair, clear the DTC with the Vanguard EFI diagnostic tool, run the engine through a full warm-up cycle under load, and confirm the fault does not return before returning the equipment to service.
Frequently Asked Questions
What does Briggs Vanguard code P0335 mean?
It means the ECM is not receiving a usable signal from the crankshaft position sensor. The ECM needs that signal to know where the crankshaft is so it can time spark and fuel injection. Without it, the engine either will not start or shuts down as soon as the signal drops out.
Can I still run the equipment with a P0335 active?
No. On Vanguard EFI engines, an active P0335 disables spark and injection firing, so the engine will not run reliably and usually will not start at all. Do not operate the equipment until the fault is resolved.
How much does it cost to fix a P0335 on a Vanguard EFI engine?
If the sensor itself is the problem, expect to spend $40-$90 for the part if you do it yourself. A shop will typically charge $120-$200 for a straightforward sensor swap including diagnosis. If the reluctor ring is damaged, add $100-$250 more for the additional labor involved in flywheel removal.
My Vanguard EFI engine starts fine when cold but stalls after 10 minutes. Is that still P0335?
Yes, that pattern is a classic sign of a crank sensor that is failing as it heats up. The sensor's internal windings or the connector expand with heat and lose contact. Confirm P0335 with the Vanguard EFI diagnostic tool when the fault is active, then replace the sensor while it is still warm to verify the root cause.