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U2045 BMW Fault Code

Check U2045 OBD Fault Code Reason
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.

U2045 Code Symptoms :

See U2045 in engine

When you turn on the ignition, the Service Engine Soon or Check Engine U2045 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 U2045!

Diagnosis And Repairing U2045

U2045 OBD2 reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.

How to fix U2045 code ?

See U2045 repair manual
  • Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
  • Faulty Air fuel ratio (A/F) Sensor 1 Bank 1
  • Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
  • Missing or loose fuel cap

As long as the throttle plate remains closed, the idling speed and quality is controlled by the PCM via the idle control valve, and as can be seen from the above it should be clear that idle control on a gasoline engine is a complex affair.

For instance, if the engine is started in sub-zero temperatures, the PCM will command the idling control valve to allow less air to enter the engine to enrich the air/fuel mixture to create a condition which is roughly analogous to how chokes worked on carburetted engines to control idling in cold weather.

BMW Cars that meet U2045 error