U2278 Alta 2-litre Diagnostic Trouble Code

U2278 Alta 2-litre code definition:
U2278 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Alta 2-litre.

U2278 Alta 2-litre is defined as Camshaft Position Sensor A Circuit Low. This means the CMP (camshaft position) sensor circuit on engine bank 1 sends an irregular reading. The PCM then uses this data to provide the right strategies for the fuel delivery and ignition timing of the engine.

Symptoms

Symptoms of a U2278 Alta 2-litre diagnostic trouble code may include:
Place of U2278 in engine

Possible Causes :

  • Faulty IMRC actuator relay (if equipped)
  • A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
  • Defective ECU strategies or components will prevent proper regeneration

Common Misdiagnoses

  1. TP Sensor Learn Not Complete Problem
  2. Low Coolant Circuit Problem
  3. Cruise Control System - Vehicle Accel Too High Problem
  4. TFP Valve Position Switch-Drive Without Drive Ratio Problem
  5. Problem

Repair Processes :

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. 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 U2278 Alta 2-litre 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 U2278 Alta 2-litre.

Fortunately, U2278 Alta 2-litre is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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