P0340 — Camshaft Position Sensor A Circuit (Bank 1 or Single Sensor)
P0340 sets when the camshaft position sensor signal is missing, erratic, or incorrect relative to the crankshaft signal. Cam/crank correlation scoping distinguishes sensor failure from mechanical timing issues. Always check cam/crank correlation — a jumped timing chain can set P0340.
Fault Overview
Failed CMP sensor, wiring issues, damaged reluctor, incorrect cam timing (stretched chain or jumped belt), air-gap problems, and oil intrusion into the connector are the primary causes. Oil leaks into the CMP connector are common on some engines.
Engine & Platform Coverage
Symptoms
- •P0340
- •camshaft position sensor
- •CMP circuit
- •P0340 correlation
- •cam sensor code
Possible Causes
- 1.Failed CMP sensor
- 2.Wiring issues
- 3.Damaged reluctor
- 4.Incorrect cam timing (stretched chain or jumped belt)
- 5.Air-gap problems
- 6.Oil intrusion into connector
Wiring & Circuit Notes
CMP sensor connector and wiring. Check for oil leaks at the sensor.
DVOM Specs & Sensor Tests
Signal while cranking or running. Correlation with CKP signal. Resistance if applicable. Scope pattern.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Scope CMP and CKP Signals Together: Scope CMP and CKP signals together. Look for missing pulses and verify correlation between the two.
- 2Step 2 — Inspect Connector for Oil or Damage: Inspect the CMP connector for oil intrusion or damage.
- 3Step 3 — Check Wiring Continuity: Check wiring continuity from the sensor to the PCM.
- 4Step 4 — Verify Mechanical Cam Timing if Correlation Is Off: Verify mechanical cam timing if the correlation is off — a jumped chain or belt can set P0340.
- 5Step 5 — Replace Sensor if Signal Is Missing and Wiring/Timing Are Good: Replace the CMP sensor if the signal is missing and wiring and mechanical timing are 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 CMP sensor $50–300; repair wiring $50–200; correct cam timing (chain/belt service) $500–1,500+.
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.