P0135

Schematic:

The heated oxygen (HO2S) bank 1 sensor 1 is threaded into the cylinder 1, 3, 5 exhaust manifold (cylinders 1, 3, 5 are closest to front of dash). The sensor is equipped with a heater to decrease the amount of time to enter closed loop fuel control for bank 1. The ECM controls the heater by supplying a ground to circuit 5038. The ECM calculates the efficiency of the sensor heating element by calculating the internal sensor (NOT HEATER) resistance based on actual current and signal voltage measurements on circuit 1665 after the engine has been running a certain length of time. As temperature increases, the sensor internal resistance will decrease. The ECM compares modeled sensor resistance values to the measured values based on the calculated sensor temperature (exhaust gas temperature). If the heater is working properly, the internal sensor resistance will decrease at a certain rate based on the exhaust gas temperature. If the resistance takes too long to decrease or is too high after a certain amount of engine run time, the heater is assumed to be heat insufficiently. DTC P0135 will set if the calculated internal sensor resistance is too high after a certain length of engine run time indicating an inefficient heating element.

DTC PARAMETERS
DTC P0135 will set if the HO2S bank 1 sensor 1 calculated sensor resistance (based on the actual signal current) is greater than 63 ohms when:
^ Engine run time is greater than 10 seconds
^ Exhaust pipe moisture has evaporated (calculated engine run time between 0 and 30 seconds)
^ Calculated converter temperature is between 350 and 585°C (626 and 1085°F)
^ Main relay voltage is between 10.5 and 18 volts
^ No HO2S bank 1 sensor 1 heater circuit DTCs have been set

DTC P0135 diagnostic runs continuously once the above conditions have been met.

P0135 is a type B DTC.

DIAGNOSTIC AIDS
If DTC P0134 is also set, diagnose that DTC first. An open in the sensor signal or sensor return may set this DTC.

Make sure no corrosion is present in the HO2S bank 1 sensor 1 harness connector and that all terminals (heater AND signal) are contacting correctly. If OK, replace the HO2S bank 1 sensor 1.

Heater element resistance: 7.0-20.2 ohms