P392C Mercedes B Class Diagnostic Trouble Code

P392C Mercedes B Class code definition:
P392C is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Mercedes B Class.

P392C Mercedes B Class 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. Other symptoms that may indicate this problem are when the Check Engine Light illuminates and when there is a visible lack of engine power.

Symptoms

Symptoms of a P392C Mercedes B Class diagnostic trouble code may include:
  • Fuel pressure too low
  • Rich or lean exhaust
  • Diminished fuel efficiency
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Place of P392C 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.
  • Faulty IMRC actuator/sensor

Common Misdiagnoses

  1. Crankshaft Position Sensor Circuit Performance Problem
  2. TP Sensor Learn Not Complete Problem
  3. Low Coolant Circuit Problem
  4. Cruise Control System - Vehicle Accel Too High Problem
  5. Kick-Down Switch Failed Short 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. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code P392C Mercedes B Class 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 P392C Mercedes B Class.

Fortunately, P392C Mercedes B Class is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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