B0187 Mercedes-Benz 250 Diagnostic Trouble Code

B0187 Mercedes-Benz 250 code definition:
B0187 is a kind of OBD-II Diagnostic B-Body Diagnostic Trouble Code for Mercedes-Benz 250.

B0187 Mercedes-Benz 250 is described as Oxygen Sensor Circuit No Activity Detected Bank 2 Sensor 1. This code appears when the PCM (powertrain control module, also known as ECM or engine control module in other brands) remains at or close the 0.450 set voltage point. This is because the barometric pressure sensor is part of the MAF sensor. Sometimes, the MAF's sensing wire can accumulate and get covered with dirt, dust and/or oil residue, which can also lead to the error code.

Symptoms

Symptoms of a B0187 Mercedes-Benz 250 diagnostic trouble code may include:
  • Faulty O2 Sensor
  • Lack of power
  • If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Place of B0187 in engine

Possible Causes :

  • An air leak forward of the DPF will change the sensor readings resulting in the code
  • Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
  • Fuel with a large percentage of sulfur will clog the DPF quickly

Common Misdiagnoses

  1. Vehicle Speed Output Circuit Problem
  2. Cruise Control Servo Indicates Low Problem
  3. A/C System High Pressure High Temperature Problem
  4. PCM Stack Overrun Problem
  5. Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. 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. Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio.

Process Tips

Diagnostic trouble code B0187 Mercedes-Benz 250 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 B0187 Mercedes-Benz 250.

Fortunately, B0187 Mercedes-Benz 250 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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