P0377 Mercedes-Benz Code - Timing Reference High Resolution Signal 'B' Too Few Pulses

P0377 indicates that the engine control module (ECM) has detected too few pulses from the high-resolution timing reference signal 'B,' which is used to monitor the crankshaft or camshaft position.

Symptoms may include poor engine performance, difficulty starting the engine, rough idling, reduced fuel efficiency, and the illumination of the check engine light.

Common causes include a faulty camshaft or crankshaft position sensor, damaged wiring or connectors in the sensor circuit, or issues within the ECM itself.

Diagnose the code by using an OBDII scanner to confirm the code, inspecting the camshaft and crankshaft position sensors, checking the wiring and connectors for damage, and testing the ECM if necessary.

While the vehicle may still be drivable, driving with this code can lead to further engine performance issues or potential damage. It is best to address the problem as soon as possible.

Repairs may involve replacing the faulty camshaft or crankshaft position sensor, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ECM if needed.

Repair costs can vary depending on the root cause. Replacing a camshaft or crankshaft position sensor may cost $150–$400, while ECM repairs or replacements can be more expensive.

Yes, a weak or failing battery can sometimes cause voltage fluctuations that may affect the sensors and trigger this code.

Yes, diagnosing and repairing this code often requires an OBDII scanner, a multimeter for electrical testing, and potentially advanced tools to reprogram the ECM.

The code may clear itself after successful repairs and normal driving cycles, but it’s recommended to clear the code manually with an OBDII scanner and verify the fix.