Diesel Trouble Codes

P0340 — Camshaft Position Sensor A Circuit — 6.0 Power Stroke

P0340 on the 6.0L Power Stroke means the PCM has detected a fault in the camshaft position (CMP) sensor circuit. On this platform a lost CMP signal can cause…

Updated October 15, 2026

What it means

Generic definition: The PCM has detected a fault in the camshaft position (CMP) sensor circuit. Typical on this platform: On the 6.0L a lost CMP signal causes crank-no-start or stalling; check the sensor, connector and wiring, and compare with CKP signal on a scan tool while cranking.1

Most likely causes

  1. CMP sensor internal failure or heat-related signal loss — The CMP sensor can fail electrically or lose signal when hot, leading to a circuit fault and loss of engine speed/position sync.1
  2. CMP sensor connector or wiring damage / chafing — Connector corrosion, loose terminals, or harness chafing (e.g., near hot or moving components) can open/short the CMP circuit.1
  3. CMP signal interference or loss due to engine speed/position sync issue — A missing or erratic CMP signal relative to CKP can set P0340; verify RPM is present on the scan tool while cranking and compare CMP vs CKP sync.12
  4. PCM power/ground or reference-voltage issue affecting CMP circuit — Poor PCM power/ground or a reference-voltage problem can manifest as a CMP circuit fault; inspect related fuses, grounds, and harness integrity.3

How to diagnose

  1. Verify symptom and freeze-frame: confirm crank-no-start, stall, or rough running with P0340 stored; note engine temp and run time.
  2. Check scan-tool data while cranking: confirm RPM is displayed (CKP present) and look for CMP sync/status; a missing CMP signal with good CKP points to CMP circuit.
  3. Inspect CMP sensor and connector: examine for oil contamination, corrosion, damaged terminals, and secure connection; check harness for chafing, heat damage, or rubbing near the engine/valve cover.
  4. Check CMP reference voltage and signal wiring integrity: with key-on, verify reference voltage at the sensor per service info and inspect continuity to PCM; repair any opens/shorts or chafed sections.
  5. Compare CMP vs CKP signals on a lab scope or scan tool while cranking: look for clean, consistent patterns and proper sync; replace CMP sensor if signal is absent/erratic and wiring checks good.
  6. Clear codes and retest: after repairs, crank/run and confirm P0340 does not return and CMP sync is maintained under hot and cold conditions.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
Shop diagnosis—1–2 hrsShop
Wiring or connector repair$10–$1001–4 hrsDIY with tools and a manual
Crankshaft or camshaft position sensor$40–$2000.5–2 hrsDIY with tools and a manual
ECM/PCM replacement (programmed)$600–$2,0001–3 hrsShop

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If the engine cranks with no start, stalls while driving, or you find damaged harness/PCM connector issues, have a qualified diesel technician diagnose and repair to avoid misdiagnosis and further damage.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources

  1. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎ ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎

  3. NHTSA owner report 10496736 ↩︎