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The heater temperature is derived by measure the heater resistance and also calculating the heater temperature utilizing the resistance versus temperature characteristic. In bespeak to measure the heater temperature, the transistor that controls the heater is momentarily disabled and also current is passed v a precision feeling resistor connected is series with the heater element. The voltage drop throughout the sense resistor offers the relationship to present which amounts to a temperature value. As soon as the temperature is acquired, the sense current is turn off and normal operation is restored.When monitored upstream O2 Sensor Heater Circuit low DTC space not active, battery voltage between 10.4 and also 15.75 volts, auto Shutdown Relay (ASD) is energized. Set condition the O2 Sensor Heater facet resistance is over the minimum agree threshold. Default action, mulfunction Indicator lamp (MIL) light will certainly illuminate.
O2 Sensor 1/1 Heater control circuit open up or high resistance.O2 Sensor 1/1 Heater floor circuit open or high resistance.O2 Sensor 1/1 Heater manage circuit shorted come voltage.O2 sensor 1/1.Powertrain manage Module (PCM).
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Step 1. Inspect for an energetic DTCIf P0688-Auto Shutdown relay feeling circuit low, has set along with any type of of the O2 Sensor Heater circuit High DTC, all of the O2 sensor heater regulate circuits should be checked for a brief to battery voltage. Test journey or operate the automobile in accordance v the as soon as monitored and set conditions. V the scan tool, check out DTC.Is the DTC active or pending ?Yes, go to action 2.No, execute the PCM intermittent condition.Step 2. Examine the O2 Sensor 1/1 Heater elementTurn the ignition off. Enable the O2 Sensor to cool under to room temperature. Disconnect the O2 Sensor 1/1 exploit connector, measure up the resistance throughout the O2 Sensor 1/1 Heater element between the O2 Sensor 1/1 Heater control terminal and the O2 Sensor 1/1 Heater ground terminal in ~ the component. O2 Sensor 1/1 Heater facet resistance values have to be measure up at21.1°C (70°F). The resistance value will differ with various temperature values.Is the O2 Sensor 1/1 Heater aspect resistance between 2.0 and 35.0 Ohms ?Yes, walk to action 3.No, verify that there is good pin come terminal call in the O2 Sensor 1/1 and also Powertrain manage Module Connectors. If no difficulties are found, change the O2 Sensor 1/1. Execute the Powertrain confirmation Test.Step 3. Inspect the O2 Sensor 1/1 Heater control circuitTurn the ignition on. Make certain the check light is probing the circuit prior to actuating the Heater check or a DTC may set and not allow the actuation. Utilizing a 12 volt test light linked to ground, probe the O2 Sensor 1/1 Heater manage circuit in the O2 Sensor 1/1 exploit connector. With the scan tool, actuate the O2 Sensor 1/1 Heater test through the sensor exploit connector quiet disconnected.The check light must be illuminated and bright proportional come the maximum duty cycle permitted by the scan tool. For example, if the scan tool permits 100% actuation, the brightness have to be as a direct link to the battery. If the scan tool allows a maximum25% actuation, the brightness should be25% together bright together a direct link to the battery.Does the test light illuminate throughout actuation ?Yes, go to action 4.No, go to step 5.Step 4. Check the O2 Sensor 1/1 Heater soil circuit for an open or high resistanceTurn the ignition off, measure the resistance in between an engine ground and the O2 Sensor 1/1 Heater ground circuit at the O2 Sensor exploit connector.Is the resistance listed below 3.0 Ohms ?Yes, verify the there is great pin come terminal call in the O2 Sensor 1/1 and also Powertrain regulate Module connectors. If no problems are found, change the O2 Sensor. Execute the execute thePowertrain confirmation Test.No, fix the O2 Sensor 1/1 Heater ground circuit for an open or high resistance.Step 5. Examine the O2 Sensor 1/1 Heater manage circuit because that a short to voltageDisconnect the PCM exploit connector, check for continuity in between the O2 Sensor 1/1 Heater regulate circuit and also other circuits in ~ the PCM exploit connector.Is there continuity in between the O2 Sensor 1/1 Heater regulate circuit and also any various other circuit ?Yes, repair the O2 Sensor 1/1 Heater regulate circuit because that a quick to the circuit that confirmed continuity.No, walk to action 6.Step 6. Examine the O2 Sensor 1/1 Heater manage circuit for an open or high resistanceTurn the ignition off, measure the resistance that the O2 Sensor 1/1 Heater manage circuit in between the O2 Sensor harness connector and also PCM harness connector.Is the resistance listed below 3.0 Ohms ?Yes, walk to action 7.No, repair the O2 Sensor 1/1 Heater regulate circuit because that an open or high resistance.Step7. Inspect related PCM and component connections