P1387 — Variable Cam Timing Solenoid #1 Circuit Malfunction

OBD2 code P1387 flags a problem with the sensor and actuator circuits (variable cam timing solenoid #1 circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.

For Ford vehicles

camshaft position timing solenoid #2 circuit Mazda

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P1387 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the variable cam timing solenoid #1 for damage, corrosion, chafing or poor contact.
Subsystem check Run the module's actuator test for the variable cam timing solenoid #1 if your scanner supports it — a component that does not respond to a direct command is confirmed faulty.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1387 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1387 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000. Overall, fixing P1387 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What are the symptoms of P1387?

Drivers most often notice: increased fuel consumption in some cases, Check Engine Light on, possible limp mode depending on the affected component, the affected system operates intermittently or not at all.

Is it safe to drive with P1387?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How do I diagnose P1387 myself?

Start with a scan: confirm P1387, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the variable cam timing solenoid #1, and verify the suspect component against live data before buying parts.

What does OBD2 code P1387 mean?

What is the most common cause of P1387?

The most common causes are: corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.

Modern engines use variable cam timing (VCT) to optimize valve opening events based on RPM and engine load. The system relies on an electronic solenoid that directs oil pressure to advance or retard the camshaft position. When the powertrain control module (PCM) detects that the Variable Cam Timing Solenoid #1 is not responding correctly to commands, it logs DTC P1387. This code specifically indicates a circuit malfunction in the first VCT solenoid circuit—the module's self-test has determined that the component or its control logic is not behaving as expected.

Unlike codes that point directly to a specific electrical fault, a general malfunction code like P1387 means the problem could be inside the solenoid itself, in the wiring feeding it, or even in the PCM's output driver that controls it. The PCM monitors the circuit continuously and runs a self-test each time the engine operates. P1387 is set only after the fault persists across multiple test cycles under specific conditions, which is why the stored freeze frame data is so useful—it tells you exactly what engine speed, load, and temperature were present when the failure occurred.

In practice, the affected vehicle will likely feel different before you even scan it. The Check Engine light comes on, fuel economy may climb noticeably, and the variable cam timing system either stops working entirely or becomes erratic. Some vehicles compensate well enough to keep driving; others drop into a reduced-power limp mode. Either way, the underlying issue needs attention rather than being ignored indefinitely.

Common Symptoms of P1387

Check Engine light illuminates and remains on
Noticeable increase in fuel consumption
Intermittent or complete loss of VCT system function
Reduced engine performance or sluggish acceleration
Engine may enter limp-home mode with limited power output
Rough idle or unstable camshaft timing under certain conditions

What Causes P1387?

The root cause is rarely mysterious, but pinpointing it requires methodical electrical diagnosis. Here are the most common culprits, ordered from most to least frequently encountered:

Damaged, corroded, or loose electrical connector at the VCT solenoid
Open or shorted wire in the solenoid control circuit
Internal winding failure in the Variable Cam Timing Solenoid #1 itself
Poor or interrupted ground connection for the solenoid circuit
Faulty PCM output driver or internal software issue in the control module
Related sensor malfunction that prevents proper VCT operation
Wiring harness chafing or insulation breakdown from heat or age

How to Diagnose P1387

Effective diagnosis follows a clear sequence from least invasive to most involved:

Connect an OBD2 scanner, record P1387, and save the freeze frame data—this snapshot of engine conditions tells you when and where the fault triggered.
Check for any other stored codes. Related DTCs often point to the primary problem; for example, a short-circuit code on the same circuit would change your diagnostic approach entirely.
Inspect the wiring harness and connector at the Variable Cam Timing Solenoid #1. Look for broken wires, melted insulation, corrosion buildup, and any signs of the connector being unplugged or damaged.
Perform an actuator test if your scan tool supports it. Commanding the solenoid to operate and getting no response confirms a failed component.
Measure reference voltage, ground integrity, and signal continuity at the solenoid connector with a multimeter. Compare readings to factory specifications.
Conduct a wiggle test on the harness while monitoring live data—if the signal drops or fluctuates, you have a broken wire inside the insulation.
After repairs, clear the code and complete a drive cycle that replicates the freeze frame conditions. Confirm that P1387 does not return.

Repair Options and Costs

Labor rates and parts pricing vary by region and shop, but the following ranges reflect typical independent shop estimates in USD:

Wiring repair or connector replacement: $80–$250
Variable Cam Timing Solenoid #1 replacement (parts and labor): $150–$500
Control module diagnosis and repair or replacement: $300–$1,000

The total cost to resolve P1387 typically falls between $80 and $1,000, depending entirely on which component is at fault. Starting with a thorough electrical inspection before buying any parts is the most cost-effective approach—the solenoid itself is rarely the problem, and control module issues are even less common. Most P1387 codes are ultimately traced back to damaged wiring or a bad connection.

Can You Drive with P1387?

Most vehicles remain drivable when P1387 is active, though you may experience lower fuel economy, reduced power, or an overall sluggish feel. The VCT system may not function at all, and the engine could enter a protective limp mode that limits RPM and throttle response. If the car starts and drives without stalling or triggering brake/steering warnings, you can continue to a repair facility at your convenience—but do not ignore the code indefinitely. Have it diagnosed and repaired before more serious symptoms develop.