P0335 — Crankshaft Position Sensor A Circuit
P0335 sets when the ECM detects a missing, erratic, or out-of-range signal from the crankshaft position sensor. Scope testing under operating conditions catches intermittent failures that static checks miss. Many CKP failures are intermittent when the engine is hot — test under operating temperature.
Fault Overview
Failed CKP sensor, damaged reluctor ring/tone wheel, wiring open or short, poor connector, air-gap issues, and intermittent failure when hot are the primary causes. A damaged tone wheel can cause intermittent P0335. Always scope the signal; a multimeter alone can miss dropouts.
Engine & Platform Coverage
Symptoms
- •P0335
- •crankshaft position sensor
- •CKP circuit
- •no start CKP
- •P0335 intermittent
Possible Causes
- 1.Failed CKP sensor
- 2.Damaged reluctor ring/tone wheel
- 3.Wiring open or short
- 4.Poor connector
- 5.Air-gap issues
- 6.Intermittent failure when hot
Wiring & Circuit Notes
CKP sensor connector and wiring. Check for chafing near the harmonic balancer or transmission bell housing.
DVOM Specs & Sensor Tests
AC voltage or digital signal while cranking. Resistance if magnetic type. Scope pattern for missing teeth or dropouts. Air gap.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
5 steps locked behind Technician Mode- 1Step 1 — Capture the CKP Signal While Cranking with a Scope: Attempt to capture the CKP signal while cranking with a scope. Look for missing pulses or dropouts.
- 2Step 2 — Inspect the Connector and Wiring: Inspect the connector and wiring for chafing near the harmonic balancer or transmission bell housing.
- 3Step 3 — Check the Tone Wheel for Damage if Accessible: Check the tone wheel for damage if accessible.
- 4Step 4 — Measure Air Gap if Specified: Measure air gap if specified by the OEM.
- 5Step 5 — Test Under Operating Temperature: If the fault is intermittent, test under operating temperature — many CKP sensors fail only when hot.
- 6Step 6 — Replace the Sensor if Signal Is Missing or Erratic: Replace the CKP sensor if the signal is missing or erratic and wiring is proven good.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Replace CKP sensor $50–300; repair wiring $50–200; repair tone wheel $200–800.
Related Codes & Pages
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Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.