U3404 Diagnostic Trouble Code

U3404 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 U3404 diagnostic trouble code may include:

Faulty PCM
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Poor acceleration
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

Possible Causes :

A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.
Faulty IMRC actuator/sensor
A large air leak at or near the number one oxygen sensor would also cause a 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. Look for damage to the tank indicating impact that may have damaged the fuel pump or sender.

Process Tips

Diagnostic trouble code U3404 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 U3404.

Fortunately, U3404 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U3404 Trouble Code For Specific Cars

U3404 Maybach Ds8 Transmission System MIL Fault
U3404 Berkeley Foursome B-pillar Power Sliding Door Open/Close Switch Input Ckt Short to Gnd
U3404 Hillman Sporting PATS Transceiver Module Signal Is Not Received
U3404 Plymouth Laser Evaporative Emission Control System Vent Control Circuit Malfunction
U3404 Chevrolet Malibu
U3404 Mercedes E 350 Accelerate Warmup Solenoid Circuit Malfunction
U3404 Lanchester De Speed Wheel LF Comparison Failure