P0503 BMW Fault Code

Description:

Catalytic converters must be warm before they can work properly. On a cold start the PCM provides a rich mixture to keep the cold engine running.
All that extra fuel goes into the catalytic converter. But the exhaust isn't very hot, because, ah, the engine is pretty cold. GM has employed several strategies to fire up the catalytic converter quicker and reduce cold start emissions. One way is to use a secondary air pump that pumps outside air directly into the catalytic converter.

P0503 Code Symptoms :

When you turn on the ignition, the Service Engine Soon or Check Engine P0503 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the P0503!

Diagnosis And Repairing P0503

P0503 OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix P0503 code ?

• Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
• Faulty spark plug (s)
• Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
• Continuous oil flow to the VCT piston chamber

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code P0503, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code P0503 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.