P0004 identifies Fuel Volume Regulator Control Circuit High. Diagnosis compares regulator command, control-line voltage, valve current, and requested versus actual rail pressure so electrical, hydraulic, and mechanical causes are separated before repair.
P2402: EVAP Leak Detection Pump Control Circuit High. The DME detects a high electrical state in the EVAP leak-detection pump control circuit. On BMW vehicles this pump is commonly part of the DMTL assembly, but circuit direction must be proven before replacing it.
P2195: O2 Sensor Signal Biased or Stuck Lean, Bank 1 Sensor 1. The DME finds Bank 1 Sensor 1 biased or stuck on the lean side. A true lean mixture, exhaust air leak, slow lambda element and signal-circuit fault produce different fuel-trim and response patterns.
P2181: Cooling System Performance. The DME judges coolant-temperature behavior implausible for operating time and load. A thermostat stuck open, inadequate circulation, trapped air, sensor bias or fan running continuously can create different temperature traces.
P2096: Post Catalyst Fuel Trim System Too Lean, Bank 1. The DME sees the Bank 1 post-catalyst mixture correction remain lean. The downstream lambda response, exhaust leakage near the sensor and upstream mixture evidence must agree before the catalyst or sensor is blamed.
P0715: Input or Turbine Speed Sensor A Circuit. The EGS cannot trust the input or turbine speed sensor A circuit. Compare turbine speed with engine and output speed before deciding between a sensor circuit problem, connector contamination and an internal transmission fault.
P0691: Cooling Fan 1 Control Circuit Low. The DME detects a low electrical state in cooling-fan control circuit 1. A signal short to ground, missing supply, harness damage, fan electronics and DME output must be distinguished before condemning the fan.
P0496: EVAP Flow During a Non-Purge Condition. The DME detects purge flow while the EVAP purge valve should be closed. A mechanically leaking purge valve is distinct from an electrical command fault and often reveals itself through idle mixture change when the purge path is isolated.
P0410: Secondary Air Injection System Malfunction. The DME does not observe the expected lean exhaust response when secondary air is commanded during a cold start. Pump delivery, non-return valve operation, hoses and blocked cylinder-head passages require separate evidence.
P050B: Cold Start Ignition Timing Performance. The DME cannot achieve or verify the ignition-timing behavior expected during the cold-start phase. Coolant-temperature plausibility, misfire distribution, fuel quality and cam/crank correlation must be judged together.
P0001: Fuel Volume Regulator Control Circuit Open. The DME detects an open electrical path in the fuel-volume regulator control circuit. This does not by itself prove low rail pressure or a failed HPFP; connector, wiring, regulator winding and driver command must be separated.
P0620 means Generator Control Circuit Malfunction. The DME records it when the charging-system control circuit or generator response does not agree with the DME command; diagnosis must prove the named circuit or mechanism before parts are replaced.