Oxygen Sensor Testing

Oxygen Sensor Output:

FAILURE MODES
Open Circuit
An open Heated Oxygen Sensor (HO2S) circuit, should set a Diagnostic Trouble Code (DTC) 13 or 63.

Low Voltage
A constant low voltage in the HO2S circuit should set a DTC 44 or 64.

High Voltage
A constant high voltage in the circuit should set a DTC 45 or 65.

FUEL SYSTEM PROBLEMS
DTCs 44, 45, 64, or 65 could also be set as a result of fuel system problems.

DIAGNOSTIC TROUBLE CODES
A problem in the HO2S circuit or fuel system should set the following DTC(s) for the indicated condition:

Open Circuit
Code 13 Bank 1 (Left) Heated Oxygen Sensor Circuit. DTC 13
OR
Code 63 Right (Bank 2) Open Oxygen Sensor Circuit. Powertrain Controls - ECM/PCM

Lean Indication
Code 44 Left (Bank 1) Oxygen Sensor Circuit (Lean exhaust). Powertrain Controls - ECM/PCM
OR
Code 64 Right (Bank 2) Oxygen Sensor Circuit (Lean Exhaust). Powertrain Controls - ECM/PCM

Rich Indication
Code 45 Left (Bank 1) Oxygen Sensor Circuit (Rich Exhaust). Powertrain Controls - ECM/PCM
OR
Code 65 Right (Bank 2) Oxygen Sensor Circuit (Rich Exhaust). Powertrain Controls - ECM/PCM

Refer to applicable DTC chart if any of the above DTCs were stored in memory.