U0203 Diagnostic Trouble Code

U0203 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 U0203 diagnostic trouble code may include:

Blown fuse (if applicable)
Engine surge
Reduction in engine performance, especially at low RPM levels
Malfunction Indicator Lamp (MIL) illuminated

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
Dirty air cleaner element Damaged DPF

Repair Processes :

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 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. 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 U0203 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 U0203.

Fortunately, U0203 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0203 Trouble Code For Specific Cars

U0203 Suzuki F1 Metering Oil Pump Position Sensor Circuit Malfunction
U0203 Renault Koleos GPS Antenna Open Circuit
U0203 Mazda Laputa Turbo Charger Bypass Valve Control Circuit
U0203 Nissan Sentra Cruise Control Command Switch Assembly Circuit Failure
U0203 Chevrolet Celta Driver Power Window Up Circuit Open
U0203 Daewoo Magnus Gate Select Position Circuit Intermittent
U0203 Lotus 49 Torque Converter Clutch System Performance