Three common Mercedes-Benz diagnostic codes are the P0101, P0172 and P0175. The P0101 indicates a Mass or Volume Air Flow Circuit Range/Performance Problem, according MercedesMedic.com. P0172 means System too Rich (Bank 1), while P0175 implies System too Rich (Bank 2).
Symptoms of a P0101 diagnostic code include engine stalling, hard starts, unstable idling and lack of power. Causes include clogging in the air filter, catalytic converter or restricted exhaust, a Malfunctioning Mass Airflow Sensor, or MAS, and vacuum leaks.
Symptoms of P0172 and P0175 include lack of power, unstable idling and misfiring. In some cases, no symptoms appear, but the Check Engine light still displays the code. Causes include a malfunctioning MAS, a defective Manifold Absolute Pressure Sensor, obsolete Powertrain Control Module software and a thermostat stuck in the open position.