Possible causes
– Faulty Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 harness is open shorted to ground
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 circuit fuse
– Faulty Engine Control Module (ECM)
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 harness is open shorted to ground
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 circuit fuse
– Faulty Engine Control Module (ECM)
Tech description
There is a factory service bulletin for the following Toyota Models:
2004 Toyota Sienna
2004 Toyota Sienna Factory Service Bulletin OBDII Code P0031
2004 Toyota Highlander
2004 Toyota Highlander Factory Service Bulletin OBDII Code P0031
2005 Toyota Avalon
2007 Toyota Avalon
2007 Toyota Camry
2008 Toyota Camry
2005 and 2007 Toyota Avalon, 2007 and 2008 Toyota Camry Service Bulletin OBDII Code P0031
When is the obd code mean?
The P0031 is set when the ECM detects an excessively low voltage through the heated oxygen sensor heater circuit
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0031 TOYOTA OBD Code Description