P0131

Diagnostic Chart:

Schematic:

The front oxygen sensors monitor the oxygen content in the exhaust gases before they enter into the pup converters. From the oxygen detected, a signal is sent to the ECM which translates this signal into a lambda value. When lambda is greater than 1, a lean condition exists. A rich condition exists when lambda is less than 1. The ECM constantly monitors the signals during the closed loop operation and compensates for a rich or lean condition by increasing or decreasing the injector pulse width. The ECM also calculates an expected lambda value based on the vehicle operating conditions. This calculated value is compared to the sensor reading. This DTC will set if the ECM detects the sensor is responding too slowly.

DTC PARAMETERS
This DTC will set under the following conditions.
^ 1400 rpm less than engine speed less than 2520 rpm
^ 0.96 less than front O2 lambda value less than 1.04
^ Closed loop operation
^ No misfire, evap, or fuel trim codes set.

DTC P0131 is a (type B) DTC

DIAGNOSTIC AIDS
To locate an intermittent problem use Scan tool to monitor HO2S Bank 1 Sensor 1 with engine idling at normal operating temperature.

Wiggling wires while monitoring the HO2S Bank 1 Sensor 1 lambda value may locate area where an open or short exists.

HO2S Bank 1 Sensor 1 wiring should be checked. Corrosion or loose connections could cause this code to set.

The most likely cause of this DTC is a slow sensor due to contamination. Contamination should be sourced before replacing sensor.

NOTE: An oxygen sensor heater element not working properly may cause this DTC to set due to the delay in reaching oxygen sensor operating temperature.