P1100 Subaru HO2S12 Sensor Circuit Voltage Too Low Air Leak

Possible causes

– Faulty Mass Air Flow Sensor
– Air leak before or after sensor
– Mass Air Flow Sensor harness is open or shorted
– Mass Air Flow Sensor circuit poor electrical connection

What about the obd code?

The Engine Control Module (ECM) detected a Mass Air Flow (MAF) sensor signal above or below calibrated limit

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1100 Subaru Description

The Mass Air Flow (MAF) Sensor circuit is monitored by the Powertrain Control Module (PCM) for sudden voltage (or air flow) input change through the Comprehensive Component Monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory Diagnostic Trouble Code (DTC) P1100 Subaru is stored.