U1721 Diagnostic Trouble Code

U1721 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 U1721 diagnostic trouble code may include:

Fuel pressure too high
Diminished fuel efficiency
Rich or lean exhaust
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Faulty IMRC actuator relay (if equipped)

Repair Processes :

Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem.

Process Tips

Diagnostic trouble code U1721 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 U1721.

Fortunately, U1721 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U1721 Trouble Code For Specific Cars

U1721 Bmw 2 Camshaft Position Sensor Circuit High Input
U1721 Alfa Romeo 179 ABS Power Relay Output Open Circuit
U1721 Bentley 4.5-litre Battery Pack Voltage Out Of Range
U1721 Singer 8 Internal ECM Malfunction
U1721 Chery A3 Double Lock Feedback Failure
U1721 Subaru K111 Left Rear Sensor Circuit Short to Vbat
U1721 Triumph 1500 Passenger's Front Seat Down Switch Circuit Short to Battery