B0852 Mercedes R 350 Diagnostic Trouble Code

B0852 Mercedes R 350 code definition:
B0852 is a kind of OBD-II Diagnostic B-Body Diagnostic Trouble Code for Mercedes R 350.

B0852 Mercedes R 350 is defined as Knock Sensor Circuit Range Performance (Bank 1 or Single Sensor). This refers to camshaft timing, which in this case is over-retarded. There are two wires dedicated for each coil; one is battery feed which usually comes from the distribution center, and the other one for the coil driver circuit from the PCM. The PCM grounds or ungrounds the circuit to activate or deactivate the coil.

Symptoms

Symptoms of a B0852 Mercedes R 350 diagnostic trouble code may include:
Place of B0852 in engine

Possible Causes :

  • Defective ECU strategies or components will prevent proper regeneration
  • The Mass Airflow sensor is a hot wire that senses the volume of air entering the intake manifold. The computer uses this information to control fuel mixture.
  • A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Common Misdiagnoses

  1. Control Module Throttle Actuator Position Performance Problem
  2. Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
  3. Cruise Vehicle Speed/Set Speed Difference Too High Problem
  4. Kick-Down Switch Failed Short Problem
  5. Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit Problem

Repair Processes :

With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. Pull the connectors apart and carefully look at the terminals (the metal parts) inside the connectors. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code B0852 Mercedes R 350 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before B0852 Mercedes R 350.

Fortunately, B0852 Mercedes R 350 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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