Camshaft Position Sensor Circuit Malfunction
What does POWERSTROKE-P0340-73 mean?
The POWERSTROKE-P0340-73 (Power Stroke) diesel fault code means: Camshaft Position Sensor Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Extended crank or no start
- Intermittent stalling
- Check Engine Light
- Rough running when hot (thermal failure)
Probable Causes (Ranked by Likelihood)
- Failed CMP (cam position sensor) -- common on 7.3L when hot Very Likely
- Damaged sensor wiring or connector Likely
- Cracked sensor housing allowing oil intrusion Possible
- PCM fault (rare) Less Likely
Step-by-Step Diagnostic Procedure
Connect scan tool (AutoEnginuity, ForScan, or IDS) and verify P0340 is active vs history.
Measure CMP signal on the yellow wire with a DVOM set to AC volts -- should pulse 0.1-1.2V AC at cranking. If it stays at 0V, sensor is dead.
Hot-soak test: let truck reach operating temp, then try a restart. Failed 7.3L CMPs often die hot and recover cold.
Inspect wiring for oil saturation near the sensor (mounted at front of engine behind harmonic balancer).
Replace with OEM Motorcraft CMP -- cheap aftermarket CMPs have a high early-failure rate on 7.3L.
Frequently Asked Questions
What is P0340 on a 7.3L Power Stroke?
P0340 on a 7.3L Power Stroke (1994-2003) indicates: Camshaft Position Sensor Circuit Malfunction. This is a known diagnostic trouble code on this engine family and typically points to the causes listed above.
Can I drive with P0340 on my Power Stroke?
Yes, you can generally drive with this code, but diagnose it soon to prevent further damage.
How much does it cost to fix P0340?
Repair cost is typically $80-$200 depending on the underlying cause and whether you DIY or use a shop. Diagnostic time alone runs $100-$180 at most independent diesel shops.