U1284 Mercedes-Benz 350 Diagnostic Trouble Code

U1284 Mercedes-Benz 350 code definition:
U1284 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Mercedes-Benz 350.

U1284 Mercedes-Benz 350 is defined as Ignition Coil B Primary/Secondary Circuit Malfunction.This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II tool, or vehicles made since 1996 up to present. 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 U1284 Mercedes-Benz 350 diagnostic trouble code may include:
  • Misfire
  • Misfire
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
  • Diminished fuel efficiency
Place of U1284 in engine

Possible Causes :

  • Faulty IMRC actuator/sensor
  • A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.
  • An air leak forward of the DPF will change the sensor readings resulting in the code

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. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code U1284 Mercedes-Benz 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 U1284 Mercedes-Benz 350.

Fortunately, U1284 Mercedes-Benz 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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