P1152 Subaru Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Rich Bank 2

Possible causes

– Faulty Oxygen Sensor
– Fuel pressure high or low
– MAF sensor dirty/defective
– Vacuum leak on engine
– Leaking fuel injector or fuel pressure regulator
– Faulty Powertrain Control Module

Symptoms

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

P1152 Subaru Description

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