U0520 Citroen 5CV is described as Fuel System Too Rich, which basically means bank 1's oxygen sensor has detected a rich condition of fuel. This means there's not enough oxygen in the exhaust from too much fuel being delivered into the air and gas mixture for combusion. The spark should have a light tan color. If the sensor probe comes with white and chalky parts, this means it has been lagging between switching phases, and should be replaced.
SymptomsSymptoms of a U0520 Citroen 5CV diagnostic trouble code may include:
Possible Causes :
Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio. If all testing has passed so far yet you still have the same code, check your scan tool and see if it can open and close the IMRC valve.
Diagnostic trouble code U0520 Citroen 5CV 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 U0520 Citroen 5CV.
Fortunately, U0520 Citroen 5CV is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.