U0078 Opel Moonlight Diagnostic Trouble Code

U0078 Opel Moonlight code definition:
U0078 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Opel Moonlight.

U0078 Opel Moonlight 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. 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 U0078 Opel Moonlight diagnostic trouble code may include:
  • Excessive exhaust leak
  • Hesitation upon acceleration
  • Malfunction Indicator Lamp (MIL) illuminated
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Place of U0078 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.
  • Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.

Common Misdiagnoses

  1. Exhaust Gas Recirculation System Valve 1 Problem
  2. BBV Sensor Circuit Low Voltage Problem
  3. Transmission Engaged At High Throttle Angle Problem
  4. Cruise Inhibit Control Circuit Problem
  5. TFP Valve Position Switch-Drive Without Drive Ratio Problem

Repair Processes :

If all testing has passed so far yet you still have the same code, check your scan tool and see if it can open and close the IMRC valve. 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.

Process Tips

Diagnostic trouble code U0078 Opel Moonlight 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 U0078 Opel Moonlight.

Fortunately, U0078 Opel Moonlight is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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