U0126 Diagnostic Trouble Code

U0126 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a U0126 diagnostic trouble code may include:

Faulty or damaged wiring
The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
Poor fuel economy
Rich or lean exhaust

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.
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Repair Processes :

You might continue by connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and freeze frame data. 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. 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.

Process Tips

Diagnostic trouble code U0126 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 U0126.

Fortunately, U0126 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0126 Trouble Code For Specific Cars

U0126 Chevrolet Nubira EGR Flow Out Of Self Test Range
U0126 Mercury Zephyr Air Suspension RF Air Spring Solenoid Output Circuit Open
U0126 Mazda Levante Turbo Charger Bypass Valve Control Circuit High
U0126 Land Rover Serie I Steering Wheel Angle Sensor Offset Failure
U0126 Zagato Zeta SCP (J1850) Invalid or Missing Data for Transmission / Transaxle / PRNDL
U0126 Toyota Allion No Movement Detected After an Unlatch During Power Open
U0126 Changhe Ideal Door Lock Cylinder Circuit Short To Battery