P0140 O2 Sensor Signal Inactive (Bank 1 Sensor 2)

P0140 code - the Downstream O2 sensor no activity diagnostic monitor is intended to diagnose  Downstream O2 sensoe that is not moving or is stuck  in a voltage window. This diagnostic is intended to verify the downstream O2 sensor ability to respond to fuel  adaption deviations during the Catalytic monitor test. To pass this monitor, the sensor must output a voltage greater than a high calibrated voltage and less than a low calibrated voltage within a calibrated time period. The test includes a non-instrusive minitor and intrusive fueling monitor. The intrusive monitor will only run if the non-intrusive test does not pass within the calibrated time period.

The intrusive fueling routine is used to 'jolt' the fuel feedback system to force the monitor to pass. A test failure accurs if the voltage pass values are not activeted after the total accumulated test time. The Oxygen sensor 1/2 signal switches from lean to rich less than 16 times within 20 seconds during monitoring. Default action the MIL light illuminate.

When monitored P0140 code:

• With the engine running.
• Vehicle speed between 32 and 88 km/h (20 and 55 mph).
• Throttle open for a minimum of 120 seconds.
• ECT greater than 70°C (158°F).
• Catalytic Converter temperature greater than 600°C (1112°F).
• EVAP purge active.

Possible causes P0140 code:

• Exhaust leak.
• O2 sensor 1/2 signal circuit.
• O2 sensor 1/2 return circuit.
• O2 sensor 1/2.

Diagnose code P0140 O2 Sensor Signal Inactive (Bank 1 Sensor 2)

Step 1. Check for an active DTC

After the repairs have been made, verify proper O2 sensor operation. If all the O2 sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 sensors.

Check for contaminants that may have damaged the O2 sensor, contaminates fuel, unnaproved silicone, oil and coolant. Start the engine, allow the engine to reach normal operating temperature. Test drive or operate the vehicle in accordance with the when monitored and set conditions. With the scan tool, read DTC.

Is the DTC active or pending?

Yes, go to step 2.

No, perform the PCM intermittent condition.

Step 2. Checking the Exhaust system for leaks

Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure (see Sitemap or labels this site)

Were any exhaust leaks found?

Yes, perform the appropriate procedure.

No, go to step 3.

Step 3. Check the O2 sensor 1/2 signal circuit

Turn the ignition off.  Disconnect the O2 sensor 1/2 harness connector. Turn the ignition on, measure the voltage on the O2 sensor 1/2 signal circuit in the O2 sensor harness connector.

Is the voltage between 4.1 and 5.0 volts?

Yes, go to step 4.

No, check the O2 sensor signal circuit for a short to ground, open or short to voltage. If OK, replace and program teh Powertrain Control  Module (PCM). Perform the PCM Verification Test procedure.

Step 4. Check the O2 sensor 1/2 return circuit

Measure the voltage on the O2 sensor 1/2 return circuit in the O2 sensor 1/2 harness connector.

Is the voltage at 2.5 volts?

Yes, go to step 5.
No, check the O2 sensor 1/2 return circuit for a short to ground, open or short to voltage. If OK, replace and program Powertrain Control Module (PCM). Perform the Powertrain Verification Test.

Step 5. Oxygen Sensor
Check for signs of contaminants that may have damaged the O2 sensor 1/2, such as contaminated fuel, unapproved silicone, oil and coolant.

Using the wiring/schematic as aguide, inspect the wiring and connectors between the O2 sensor 1/2 and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Perform any Service Bulletins that may apply.

Were any problems found?

Yes, repair as necessary.
No, replace the Oxygen sensor 1/2.

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