What's the 4c5e BMW fault code?

If You're receiving the diagnostic trouble code (DTC) 4C5E on a BMW vehicle, You're looking at an issue with Your diesel particulate filter, or DPF for short. This is, predictably, a diesel-specific code; it is commonly accompanied by 4CF3, which indicates an issue with the exhaust backpressure sensor. If You receive both codes in tandem, then it's likely that You'll need to look to the backpressure sensor for Your issue, and You'll likely need to replace it. This is because a sensor failure will often set the DPF code as well, so You'll need to be aware of comingling factors. If You're getting 4C5E and no other codes, then Your DPF is to blame, and You'll need to either thoroughly clean or potentially replace the filter.