U209U Diagnostic Trouble Code

U209U 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 U209U 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 :

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. Now, clear the codes and test-drive the vehicle to see if the code is reset. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code U209U 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 U209U.

Fortunately, U209U is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U209U Trouble Code For Specific Cars

U209U Alfa Romeo Sprint Air Bag Crash Sensor #2 Feed/Return Circuit Short To Ground
U209U Volvo 850
U209U Ferrari Rossa Key Off Voltage Low
U209U Opel Monza Door Ajar LR Circuit Failure
U209U Bristol 412 Crankshaft Position Camshaft Position Correlation (Bank 2 Sensor B)
U209U Seat Bolero Injector Circuit Open / Shorted - Cylinder #3
U209U Rumpler Tropfenwagen Ignition Run Circuit Failure