U3720 Diagnostic Trouble Code

U3720 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 U3720 diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
Reduction in engine performance, especially at low RPM levels

Possible Causes :

A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
Faulty IMRC actuator/sensor

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. 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.

Process Tips

Diagnostic trouble code U3720 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 U3720.

Fortunately, U3720 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U3720 Trouble Code For Specific Cars

U3720 Champion 400 Door Lock Cylinder Circuit Failure
U3720 Bmw R 1200 Gs Clutch position ckt short to battery
U3720 Maserati Mistral Transmission Fluid Pressure Sensor/Switch F Circuit Range/Performance
U3720 Hispano Suiza Barcelona Pedal Correlation PDS2 and HPDS
U3720 Wartburg De Luxe
U3720 Vauxhall Agila Power Window RR Motor Circuit Failure
U3720 Zagato Bambu SCP (J1850) Invalid or Missing Data for Tires