P0134

Diagnostic Chart:

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 an electrical source that responds to oxygen content in the exhaust manifold. When the sensor reaches approximately 316°C (600°F), it is fully functional and produces a voltage based on the difference in oxygen between the atmosphere and exhaust gas. The ECM sends a 450 mV bias voltage on the signal line, which is pulled up through high resistance. When the HO2S bank 1 sensor 1 is cold, it produces no voltage and has extremely high internal resistance. The internal resistance of the sensor is much greater than the resistance of the bias pull-up resistor. However, when the sensor heats up, it produces voltage that overrides the bias voltage. This voltage is read by the ECM to determine a rich/lean HO2S bank 1 sensor 1 signal used to adjust injector pulse width. Under normal conditions, low sensor voltage means high oxygen content/lean air-fuel mixture and vice versa. Normal sensor readings will fluctuate between 60 mV and 1080 mV. DTC P0134 will set if the HO2S bank 1 sensor 1 signal is inactive for a certain length of time.

DTC PARAMETERS
DTC P0134 will set if HO2S bank 1 sensor 1 signal is inactive (not fluctuating outside of the 400 mV to 538 mV range) when:
^ Condition exists for longer than 6.4 seconds
^ Exhaust pipe moisture has evaporated (calculated engine run time between 0 and 30 seconds), then engine must run for longer than 80 seconds
^ Commanded air/fuel ratio is 14.7 to 1
^ Calculated exhaust gas temperature is less than 800°C (1472°F)
^ Main relay voltage is greater than 10.5 volts

OR

Both HO2S bank 1 sensor 1 and HO2S bank 1 sensor 2 signals are greater than 200 mV when:
^ Condition exists for longer than 0.1 seconds
^ ECM is in fuel cutoff mode for longer than 3 seconds
^ Exhaust pipe moisture has evaporated (calculated engine run time between 0 and 30 seconds) then engine must run for longer than 80 seconds
^ Calculated converter temperature is less than 800°C (1472°F)
^ Main relay voltage is greater than 10.5 volts

OR

HO2S bank 1 sensor 1 calculated internal resistance is greater than 20k ohms when:
^ Exhaust pipe moisture has evaporated (calculated engine run time between 0 and 30 seconds), then engine must run or longer than 80 seconds
^ Commanded air/fuel ratio is 14.7 to 1
^ Calculated exhaust gas temperature is between 600 and 800°C (1112 and 1472°F)
^ Main relay voltage is greater than 10.5 volts

DTC P0134 diagnostic runs continuously once the above conditions have been met.

P0134 is a type B DTC.

DIAGNOSTIC AIDS

IMPORTANT: If an HO2S bank 1 sensor 1 heater circuit or heater performance DTC is also set, diagnose that DTC first. An inoperative heater will slow down sensor activation time and may set this DTC.

To locate an intermittent problem, use Scan tool to monitor HO2S BANK 1 SENSOR 1 voltage with engine running at normal operating temperature. Bias voltage (450 mV) will appear On Scan tool if an open anywhere in the sensor circuit exists.

Normal Scan tool readings in closed loop for bank 1 will vary between 60 mV and 1080 mV.