B1387 — Oil Temperature Sensor Circuit Open #

Note: The code description may vary depending on the vehicle manufacturer (OEM). Always refer to your specific service manual for the most accurate definition.

• Oil Temperature Sensor Circuit Open (Ford, General Motors, Chrysler)
• Engine Oil Temp Sensor Circuit/Open (Toyota)
• Engine Oil Temperature Sensor Signal Open (Honda, Nissan)

Summary of DTC B1387 #

The B1387 code indicates that the vehicle’s control module has detected an open circuit in the oil temperature sensor wiring. This sensor monitors the temperature of the engine oil and sends data to the engine control module (ECM) or body control module (BCM), depending on the manufacturer. An “open circuit” means the electrical path is interrupted, usually due to a broken wire, disconnected sensor, or corroded connector. This can affect engine performance and lubrication monitoring, as temperature data is essential for optimal operation. Prompt diagnosis is recommended to avoid potential engine damage due to inaccurate oil temperature readings.

Common Symptoms for Code B1387 #

When a B1387 code is present, the vehicle may exhibit subtle or obvious changes in operation. Symptoms are often related to how the engine control system compensates for missing oil temperature information. Here’s what you might notice:

• Engine warning light (MIL or CEL) illuminated
• Temperature gauge for oil may stop working or read abnormally
• Hard starting or longer cranking times, especially in cold weather
• Poor engine performance or rough idle in some models
• Possible limp mode activation on certain vehicles
• Oil change reminder or maintenance messages appearing prematurely

Probable Causes for Code B1387 #

Several factors can trigger the B1387 code, but some issues are more common than others. The most frequent causes include:

1. Faulty or damaged oil temperature sensor
2. Open or broken wiring in the oil temperature sensor circuit
3. Disconnected or corroded sensor connector
4. Shorts or high resistance in the sensor wiring harness
5. Fault in the control module (rare)

Step-by-Step Diagnosis for Code B1387 #

Diagnosing a B1387 code requires patience and a systematic approach. Here’s how a technician or skilled DIYer should proceed:

• Verify the code with a professional scan tool and check for related codes
• Locate the oil temperature sensor (refer to the OEM service manual for exact position)
• Visually inspect the sensor and wiring for damage, corrosion, or loose connections
• Disconnect the sensor and check for bent or pushed-out pins in the connector
• Test the sensor’s resistance with a digital multimeter (compare to OEM specs)
• Check for continuity and shorts to ground or power in the sensor wiring harness
• If all checks pass, test the signal at the control module side
• As a last resort, consider possible ECM/BCM faults (rare)

Possible Repairs for Code B1387 #

Once the root cause is confirmed, repairs should directly address the specific fault. Common remedies for a B1387 code include:

• Replace the oil temperature sensor if it is out of specification
• Repair or replace damaged, broken, or corroded wiring in the sensor circuit
• Clean and securely reconnect any corroded or loose sensor connectors
• Clear the code and retest the system to verify the repair
• In rare cases, replace the control module if all other causes are eliminated

Can You Drive with Code B1387? #

Limited: While your vehicle may still run with a B1387 code, it is not recommended to ignore the issue. Operating without accurate oil temperature data can lead to improper engine management, increasing the risk of long-term engine wear, especially in extreme weather conditions. Address the issue as soon as possible to avoid potential engine damage or unexpected drivability problems.

Vehicles Most Commonly Affected by B1387 #

The B1387 code is seen across many modern vehicles, particularly in models where the oil temperature sensor is crucial for engine management. It is most often reported in:

• Ford F-Series and Explorer (2005+)
• Chevrolet Silverado and Tahoe
• Chrysler 300 and Dodge Charger
• Toyota Camry and Highlander
• Honda Accord (select years)
• Nissan Altima and Maxima

Common Mistakes & Best Practices for Code B1387 #

It’s easy to overlook some key steps or make assumptions when dealing with a B1387 code. Avoid these pitfalls and follow industry best practices:

• Do not replace the sensor before thoroughly inspecting the wiring and connector
• Avoid clearing codes without addressing the actual cause—this can mask the problem temporarily
• Always use OEM or high-quality replacement parts
• Consult the specific wiring diagram for your vehicle model to avoid misdiagnosis
• Document your diagnostic steps for future reference

Express FAQ for Code B1387 #

Here are some quick answers to common questions about the B1387 code:

• Q: Will this code cause my engine to overheat?
  A: The code itself won’t cause overheating, but if the engine runs with incorrect oil temperature data, it may not protect itself properly under stress. Always monitor your temperature gauges closely.
• Q: Can I just unplug the sensor to clear the code?
  A: No. Unplugging the sensor will keep the code active and may trigger additional faults. The circuit must be repaired and the code cleared with a scan tool after a successful fix.