Faulty CYP sensor (internal failure or damaged winding); Damaged or corroded electrical connector at the CYP sensor or distributor; Chafed, cracked, or broken wires in the CYP sensor circuit (intermittent open or short); Poor ground connection for the sensor or PCM; Failing distributor assembly (on models where the CYP sensor is inside the distributor); PCM internal fault (rare, but possible after other causes are ruled out)

DTC codes / Honda codes / P1381

P1381 · HondaCYP Sensor A Intermittent Interruption

Q: What does code P1381 mean?

CYP Sensor A Intermittent Interruption. P1381 on Honda vehicles means the powertrain control module (PCM) has detected an intermittent interruption in the signal from the CYP sensor A, which is the cylinder position sensor used to identify cylinder number one for sequential fuel injection and ignition timing. The PCM sets this code when the CYP signal drops out or becomes erratic for a brief period, often without the engine stalling.

P1381 on Honda vehicles means the powertrain control module (PCM) has detected an intermittent interruption in the signal from the CYP sensor A, which is the cylinder position sensor used to identify cylinder number one for sequential fuel injection and ignition timing. The PCM sets this code when the CYP signal drops out or becomes erratic for a brief period, often without the engine stalling.

SystemPowertrain

Code typeHonda specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Intermittent rough idle or misfire that may come and go
Occasional engine stumble or hesitation during acceleration
Hard starting or extended cranking in some cases
Poor fuel economy or reduced power if the signal interruption is frequent

Common causes, most likely first

Faulty CYP sensor (internal failure or damaged winding)
Damaged or corroded electrical connector at the CYP sensor or distributor
Chafed, cracked, or broken wires in the CYP sensor circuit (intermittent open or short)
Poor ground connection for the sensor or PCM
Failing distributor assembly (on models where the CYP sensor is inside the distributor)
PCM internal fault (rare, but possible after other causes are ruled out)

How to diagnose and fix it

Inspect the CYP sensor connector and wiring for corrosion, loose pins, or chafing; repair as needed
Check the CYP sensor resistance and compare to factory specifications; replace if out of range
Perform a wiggle test on the sensor harness while monitoring CYP signal with a scan tool or oscilloscope to catch intermittent faults
Verify good ground and power supply to the sensor circuit
If the sensor is inside the distributor, inspect the distributor shaft, reluctor, and internal wiring; replace the distributor assembly if faulty
Clear the code and test-drive to confirm the repair; if the code returns, recheck the PCM and all circuit connections

Intermittent CYP faults often hide in the harness

A CYP sensor that tests fine when cold can still fail intermittently when hot, so always perform tests both cold and after warming the engine.
The CYP sensor shares its connector and part of its harness with the TDC and CKP sensors on many Honda distributors, so a single damaged wire can set multiple codes.
A loose or worn distributor bearing can cause the reluctor to contact the CYP sensor, creating an intermittent signal without any visible wire damage.
Some aftermarket distributors have poorly crimped internal wiring that causes P1381 only at certain RPMs or temperatures, so OEM-quality replacements are preferred.
P1381 can be set by a momentary voltage drop on the sensor ground circuit, which is often overlooked when only the sensor itself is tested.

Can I keep driving with P1381?

You can usually drive the vehicle short distances with P1381, but avoid sustained high-speed driving or heavy loads until the fault is repaired, because an intermittent CYP signal can cause sudden misfires or stalling that may compromise safety.

Tools that help

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Guidance is general and written for Honda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.