P0387 Mercedes-Benz Code - Crankshaft Position Sensor 'B' Circuit Low Input
Quick Answer
The Crankshaft position sensor also known as the crank position sensor is an electronic device used in an engine to record the rate at which the crankshaft is spinning. Common causes include Faulty crankshaft position sensor, Crankshaft position sensor harness is open or shorted, Crankshaft position sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0387 Mercedes-Benz indicates Crankshaft Position Sensor 'B' Circuit Low Input.
- Common causes
- Common causes include Faulty crankshaft position sensor, Crankshaft position sensor harness is open or shorted, Crankshaft position sensor circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0387 Mercedes-Benz Description
When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change. The changing gap causes the magnetic field near the sensor to change. The change in the magnetic field cause the voltage from the sensor to change.
What are the Possible Causes of the DTC P0387 Mercedes-Benz?
- Faulty crankshaft position sensor
- Crankshaft position sensor harness is open or shorted
- Crankshaft position sensor circuit poor electrical connection
- Signal plate may be damage
- Starter motor may be faulty
- Starting system circuit
- Dead or weak battery
How to Fix the DTC P0387 Mercedes-Benz?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0387 Mercedes-Benz code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0387 Mercedes-Benz Code
1. What does the OBDII code P0387 mean for a Mercedes-Benz?
P0387 indicates a "Crankshaft Position Sensor 'B' Circuit Low Input," meaning the engine control module (ECM) is detecting a low voltage or disruption in the signal from the crankshaft position sensor "B."
2. What are the common symptoms of a P0387 code in a Mercedes-Benz?
Symptoms may include difficulty starting the engine, stalling, rough idling, reduced engine performance, and the check engine light illuminating.
3. What causes the P0387 code to be triggered in a Mercedes-Benz?
Possible causes include a faulty crankshaft position sensor, damaged wiring or connectors, a misaligned sensor, or issues with the ECM.
4. Can I drive my Mercedes-Benz with a P0387 code?
Driving with this code is not recommended, as it can lead to poor engine performance or stalling, which may compromise safety.
5. How do I diagnose the P0387 code in my Mercedes-Benz?
Check the crankshaft position sensor for damage, inspect the wiring and connectors for corrosion or breaks, and test the sensor’s voltage and resistance using a multimeter.
6. How is the P0387 code repaired in a Mercedes-Benz?
Repairs may involve replacing the crankshaft position sensor, fixing or replacing damaged wiring, cleaning corroded connectors, or reprogramming the ECM if necessary.
7. What tools are needed to fix a P0387 code in a Mercedes-Benz?
Common tools include an OBDII scanner, a multimeter, basic hand tools, and possibly a Mercedes-Benz-specific diagnostic tool for ECM updates.
8. How much does it cost to fix a P0387 code in a Mercedes-Benz?
The cost can vary but typically ranges from $150 to $300 for parts and labor, depending on the severity of the issue and local labor rates.
9. Can a weak battery cause a P0387 code in a Mercedes-Benz?
Yes, a weak or failing battery can cause voltage issues, potentially leading to this code being triggered.
10. Do I need to clear the P0387 code after repairs on my Mercedes-Benz?
Yes, after completing the repairs, clear the code with an OBDII scanner and test-drive the vehicle to ensure the issue is resolved.
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