1. Meaning of Code P1393
Code P1393 generally indicates:
“Camshaft Position (CMP) Sensor Circuit Problem – Range/Performance”
Key difference from P1392:
- P1392: CKP and CMP correlation problem
- P1393: Specific CMP circuit failure
2. Main Causes
A. Electrical Problems (70%)
- Faulty CMP sensor
- Short circuit or open circuit in wiring
- Corroded or loose connector
- Power supply issue (low voltage)
B. Mechanical Problems (20%)
- Physical damage to sensor
- Metal deposits on sensor
- Excessive camshaft play
C. Other Causes (10%)
- Control module (ECU) problem
- Electromagnetic interference
- Incorrect engine timing
3. Diagnostic Procedure
Step 1 – Basic Checks
- Visual inspection of sensor and wiring
- Check connectors for corrosion
- Check engine oil level
Step 2 – Electrical Tests
| Test | Method | Normal Values |
|---|---|---|
| Power supply voltage | Multimeter (ignition ON) | 5V or 12V (depending on model) |
| Sensor resistance | Multimeter (sensor disconnected) | 250-1000 ohms |
| Output signal | Oscilloscope (engine running) | Regular square signal |
Step 3 – Advanced Checks
- Sensor data analysis with diagnostic tool
- Check mechanical timing
- Wiring resistance test
4. Recommended Solutions
- Replace CMP sensor (use OEM parts)
- Repair wiring if necessary
- Clean connectors
- ECU software update (if applicable)
5. Frequently Affected Models
- Honda Civic (1.8L R18)
- Toyota Corolla (1.8L 2ZR-FE)
- Ford Focus (2.0L Duratec)
- Chevrolet Cruze (1.4L LUJ)
6. Repair Costs
| Service | Average Cost (USD) | Duration |
|---|---|---|
| Sensor replacement | $80-$200 | 0.5-1h |
| Wiring repair | $100-$300 | 1-2h |
| Professional diagnosis | $50-$120 | 0.5h |
7. Prevention Tips
- Perform regular oil changes
- Periodically inspect wiring
- Use quality parts
- Avoid aggressive engine washes
8. Technical FAQ
Q: Can I drive with a P1393?
→ Risky – Can cause starting and performance problems
Q: How to differentiate P1393 from P0340?
→ P1393 indicates a performance/range problem, P0340 a circuit problem
Q: Can an aftermarket sensor cause this code?
→ Yes, low-end sensors have a high failure rate
9. Reset Procedure
- Fix root cause
- Clear codes with OBD2 scanner
- Perform verification drive cycle
10. Conclusion
Code P1393 requires a methodical approach:
- Complete electrical verification
- Mechanical inspection
- Sensor and circuit testing
For lasting repair, it is recommended to:
- Use quality parts
- Thoroughly check wiring
- Consult a professional for complex diagnostics
Note: Exact specifications vary by vehicle model and year. Always consult your vehicle’s specific repair manual.