U148D Diagnostic Trouble Code

U148D 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 U148D diagnostic trouble code may include:

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
Faulty or damaged wiring
Hesitation upon acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

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.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs. 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 U148D 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 U148D.

Fortunately, U148D is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U148D Trouble Code For Specific Cars

U148D Packard 300 DPFE Circuit Low Input
U148D Maserati Coupe Transmission Fluid Pressure Sensor/Switch D Circuit
U148D Maserati Gransport Transmission Fluid Pressure Sensor/Switch D Circuit Intermittent
U148D Nissan Presage COURTESY LAMP OUTPUT Failure
U148D Ferrari 255 Input/Turbine Speed Sensor Circuit Malfunction
U148D Mg C-type Air Suspension RR Air Spring/Shock Solenoid Output Circuit Open
U148D Aston Martin Bulldog Air Suspension Ride Height Select Switch Circuit Failure