Possible causes

– Faulty O2 Sensor
– O2 Sensor harness is open or shorted
– O2 Sensor circuit poor electrical connection

Symptoms

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

P1133 VOLKSWAGEN Description

A Heated Exhaust Oxygen (HO2S) sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.