P1381
Cylinder Position (CYP) Sensor Intermittent Interruption
What could P1381 mean for your vehicle?
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The P1381 code is a Honda-specific code indicating that the Cylinder Position (CYP) sensor is experiencing intermittent signal interruptions. The CYP sensor detects the position of the No. 1 cylinder to enable the ECM to control sequential fuel injection — delivering fuel to each cylinder in the correct firing order. When this signal drops out intermittently, the ECM may temporarily lose its ability to properly sequence fuel injection.
Symptoms tend to be intermittent and unpredictable. You might notice occasional rough running, a momentary stumble during acceleration, or intermittent hard starting. The Check Engine light may come on and then turn off after several drive cycles. This makes the code frustrating to diagnose because the problem may not be present when you take the car to a mechanic.
The CYP sensor is built into the distributor on most affected Honda engines and cannot be replaced independently. Start by inspecting the connector at the distributor for looseness or corrosion — this is the most common and cheapest fix. If the connector is fine, wiggle-test the wiring harness while the engine is running to try to reproduce the fault. If the sensor itself is failing, the distributor assembly will need to be replaced.
Severity
Symptoms
- •Intermittent engine misfiring
- •Check Engine light may come on and off
- •Occasional rough idle
- •Engine hesitation or stumbling
- •Intermittent hard starting
- •Possible stalling at random intervals
Likely Causes
Loose, corroded, or vibration-damaged connectors at the Cylinder Position sensor plug cause intermittent signal dropouts.
Heat and vibration can cause wires in the CYP sensor circuit to develop intermittent breaks or shorts.
The CYP sensor integrated into the distributor can degrade over time, producing intermittent rather than consistent failures.
Excessive play in the distributor shaft or internal wear can cause the CYP sensor to lose its reference intermittently.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Clean and reseat the CYP sensor electrical connector
- Repair or replace damaged wiring in the sensor circuit
- Replace the distributor assembly (which contains the CYP sensor)
- Check distributor shaft for excessive play or wear
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