U0078 Standard Ten Diagnostic Trouble Code

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

U0078 Standard Ten is defined as Knock Sensor Circuit Range Performance (Bank 1 or Single Sensor). This refers to camshaft timing, which in this case is over-retarded. 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 U0078 Standard Ten diagnostic trouble code may include:
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. 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 :

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 Standard Ten 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 Standard Ten.

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

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