P1387

What it means

P1387 on a Honda means the engine control unit has received no signal from cylinder position (CYP) sensor B, which is a camshaft-position type sensor. The unit expects pulses from this sensor while the engine is cranking or running, and it saw none. Which sensor is 'B' depends on the engine and model, so confirm this against the model-specific data.

Symptoms

• Malfunction indicator lamp on
• Engine cranks but is hard to start or will not start
• Engine stalls unexpectedly or cuts out intermittently
• Rough running, hesitation or poor power
• Poor fuel economy
• Other related cam or crank position codes stored

Possible causes

• Damaged, chafed or broken wiring to the CYP sensor B (open circuit, short to earth or short to supply)likely
• Corroded, loose or contaminated sensor connectorlikely
• Failed CYP sensor Blikely
• Missing or damaged reluctor or trigger wheel on the camshaft or distributor, or a loose sensor mountingpossible
• Incorrect cam timing, such as a jumped or slipped timing belt or chain, giving a poor or absent signalpossible
• Poor sensor supply or earth, or a blown fuse feeding the sensor circuitpossible
• Fault inside the engine control unitrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine speed, coolant temperature and whether the engine was running or cranking when the code set
2. Check for related cam or crank sensor codes, which point towards timing or a shared supply or earth problem
3. Visually inspect the CYP sensor B wiring, routing and connector for chafing, heat damage, oil contamination, corrosion and bent or pushed-back pins
4. Check the sensor is fitted securely, undamaged and clean, with the correct air gap or seating where applicable
5. Watch live data for engine speed and cam signal status while cranking to see if the unit sees any pulses
6. Test the sensor supply voltage, earth and signal wire for continuity and shorts against the wiring diagram for that model and engine
7. Inspect the trigger wheel or reluctor for damage or debris, and check cam timing marks against the manufacturer procedure
8. Check the sensor output with an oscilloscope if the wiring tests good, and compare it with the crank signal

How to fix

• Repair or replace damaged wiring and clean or replace corroded connector terminals
• Replace the CYP sensor B if it fails testing, then clear the code and confirm it stays clear
• Refit or secure a loose sensor and replace a damaged trigger wheel or reluctor
• Correct the cam timing, and replace worn timing components if they caused the fault
• Restore a faulty supply or earth or replace a blown fuse, after finding out why it failed
• Investigate or replace the engine control unit only after all wiring, sensor and timing causes are ruled out

Can I keep driving?

This code for other makes

• P1387AcuraCYP Sensor B No Signal
• P1387InfinitiCYP Sensor B No Signal
• P1387MazdaCamshaft Position Timing Solenoid 2 Circuit
• P1387OtherVariable Cam Timing Solenoid #2 Circuit Malfunction
• P1387VolkswagenControl Unit Internal Altitude Sensor

Nearby codes

• P1386HondaCYP Sensor B Intermittent Interruption
• P1456HondaEvaporative Emission Control System Leak Detected Fuel Tank System