P0140 Acura HO2S12 Sensor Circuit No Activity Detected

Description

OBD-II Trouble Code Description for P0140 Acura

O2 Sensor Circuit No Activity Detected

What does this mean?

OBD2 Code P0140 Acura definition:
The Powertrain control module (PCM) will provide a .45 volt reference voltage to the Oxygen sensor. When the O2 sensor reaches operating temperature, it will generate a voltage that will vary depending on the oxygen content of the exhaust. Lean exhaust generates a low voltage (less than .45V) and rich exhaust generates a high voltage (greater than .45V). O2 sensors on a specific bank marked as “sensor 2” (as this one is) are used to monitor emissions. A Three-Way Catalyst (TWC) system (catalytic converter) is used to control tailpipe emissions. The PCM uses the signal received from Oxygen sensor 2 (#2 indicates aft of catalytic converter, #1 indicates pre-converter) to read efficiency of TWC. Normally this sensor will switch between high and low voltage at a noticeably slower rate than the front sensor. This is normal. If the signal received from rear (#2) O2 sensor indicates that the voltage has “stuck” between .425V to .474 V, the PCM determines this sensor is inactive and this code will set.

Symptoms

Possible sumptoms of OBD code P0140 Acura
Your check engine light(CEL), or malfuction indicator lamp (MIL) will be illuminated. There will not likely be any noticeable drivability problems other than the MIL. The reason is this: The rear or post catalytic converter Oxygen sensor does not affect fuel deliver(this is an exception on Chryslers). It only MONITORS the efficiency of the catalytic converter. For this reason, you will likely not notice any engine trouble.

Causes

Possible causes of OBD code P0140 Acura
The causes for a P0140 Acura code are fairly few. They could be any of the following: Shorted heater circuit in O2 sensor. (Usually requires replacement of heater circuit fuse in fuse block also) Shorted signal circuit in O2 sensor Melting of harness connector or wiring due to contact with exhaust system Water intrusion in harness connector or PCM connector Bad PCM

Possible Solutions

This is a fairly specific problem and shouldn’t be too difficult to diagnose. First, start engine and warm up. Using a scan tool, watch the Bank 1, sensor 2, o2 sensor voltage. Normally the voltage should switch slowly above and below .45 volts. If it does, the problem is likely intermittent. You’ll have to wait for the problem to surface before you can accurately diagnose. However, if it doesn’t switch, or is stuck then perform the following: 2. Shut off vehicle. Visually check the Bank1,2 harness connector for melting or chafing of the harness or the connector. Repair or replace as needed 3. Turn ignition on, but engine off. Disconnect the O2 sensor connector and check for 12Volts at the Heater Circuit supply and for proper ground on the heater circuit ground circuit. a. If 12V heater supply is missing, check the proper fuses for an open in the circuit. If heater circuit fuse is blown, then suspect a bad heater in the o2 sensor causing a blown heater circuit fuse. Replace sensor and fuse and recheck. b. If ground is missing, trace the circuit and clean or repair ground circuit. 4. Next, with connector still unplugged, check for 5 Volts on the reference circuit. If this is missing, check for 5 Volts at the PCM connector. If 5 Volts is present at the PCM connector but not at the o2 sensor harness connector, then there is an open or short in the reference wire supply between the PCM and the o2 sensor connector. However, if there is no 5 Volts present at the PCM connector, the PCM is likely at fault due to internal short. Replace PCM. ** (NOTE: on Chrysler models, a common problem is the 5Volt reference circuit can be shorted out by any sensor on the car that uses a 5 Volt reference. Simply unplug each sensor one at a time until the 5 Volts reappears. The last sensor you unplugged is the shorted sensor. Replacing it should fix the 5 Volt reference short.) 5. If all the voltages and grounds are present, then replace the Bank 1,2 O2 sensor and re-test.

The OBD2 Code Information Be Applicable For Acura:

2014 Acura RLX,2014 Acura MDX,2013 Acura SUV-X Concept,2013 Acura RDX,2013 Acura NSX Concept,2013 Acura MDX Concept,2013 Acura ILX Endurance Racer,2013 Acura ILX,2012 Acura TL,2012 Acura RLX Concept,2012 Acura NSX Concept,2012 Acura ILX Street Build Concept,2012 Acura ILX Concept,2011 Acura TSX Sport Wagon,2011 Acura TSX Sedan,2010 Acura ZDX,2010 Acura TSX V6,2010 Acura RDX,2010 Acura MDX,2009 Acura ZDX Concept,2009 Acura TSX,2009 Acura TL,2009 Acura RL,2007 Acura TSX,2007 Acura TL Type-S,2007 Acura TL,2007 Acura RDX,2007 Acura MDX,2007 Acura Advanced Sports Car Concept,2006 Acura RDX Prototype,2006 Acura MD-X Concept,2006 Acura Advanced Sedan Concept,2005 Acura TSX A-Spec Concept,2005 Acura TSX,2005 Acura TL,2005 Acura RSX Type-S,2005 Acura RSX A-Spec Concept,2005 Acura RSX,2005 Acura RL with ASPEC Performance Package,2005 Acura RL ASPEC Concept,2005 Acura RL,2005 Acura RDX Concept,2005 Acura NSX,2005 Acura MDX,2004 Acura TL with ASPEC Performance Package,2004 Acura TL 25 Hours of Thunderhill,2004 Acura RL Prototype,2004 Acura 3.2 TL,2003 Acura TL ASPEC Concept,2003 Acura 3.2 CL Type-S,2002 Acura NSX sketches,2001 Acura NSX-T,2001 Acura Integra

Note:

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