P1387

Variable Cam Timing Solenoid #1 Circuit Malfunction

Powertrain Emission Controls Variable Valve Timing 🟡 Moderate — Fix within a week ⚠️ Drive with Care
💬

What This Actually Means

In plain language — no jargon

The engine's variable cam timing solenoid #1 isn't working properly, so the ECU can't adjust valve timing like a broken gear shifter stuck in one position. This causes the engine to run inefficiently and may trigger the check engine light.

⚡

Symptoms You May Notice

3 known symptoms for this code
Check engine light illuminated
Rough idle or engine hesitation during acceleration
Reduced fuel economy and loss of power
🔬

How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the solenoid's electrical circuit resistance, current draw, and response time when commanding variable cam timing adjustments. It compares actual camshaft position feedback against expected timing based on engine load and RPM. If the solenoid fails to energize or the circuit shows abnormal resistance, a fault is triggered.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Solenoid Coil Resistance 4-8 ohms Open circuit (>25 ohms) or short (<1 ohm)
Camshaft Timing Response Within 2° of target timing Timing drift >5° or no change detected
🔧

Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Electrical connector and wiring harness
Inspect and reseat the solenoid connector; check for corrosion, loose pins, or damaged wiring and clean contacts with electrical contact cleaner.
2
Engine oil and filter
Change engine oil and filter as contaminated oil can cause solenoid stiction; use manufacturer-recommended grade.
3
Variable cam timing solenoid #1
Replace the solenoid if electrical checks pass; remove the mounting bolt and connector, then install new unit with fresh sealing washer.
⚠️

When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P1387 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
🔄

How to Clear Code P1387

What happens after you fix the fault

Once the fault is repaired, P1387 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.