P0157 Acura O2 Sensor Circuit Low Voltage Bank 2 Sensor 2

Description

OBD-II Trouble Code Description for P0157 Acura

O2 Sensor Circuit Low Voltage

What does this mean?

OBD2 Code P0157 Acura definition:
This code definition:a fault in the post-catalyst o2 sensor on Bank 2. First, a basic run-down of the catalyst: The Catalytic Converter is used to help control tailpipe emissions, to “clean up” the exhaust, if you will. The PCM (Powertrain Control Module) uses the signal from the heated oxygen sensor to the rear of the catalyst to monitor the catalyst’s efficiency by comparing it to the o2 sensors in front of the catalyst. If the PCM sees little or no difference between the exhaust quality in post- and pre- catalyst sensors then it knows that the catalyst is not working properly. To over simplify: a post-cat sensor’s main job is to monitor catalyst efficiency, not control fuel management (although they can have a measure of influence over the front o2 sensor’s operation, we’ll just stick to basics for the sake of simplicity). If you have a P0157 Acura, that doesn’t mean your catalyst is bad (in fact, it usually never does). This code basically means that the Bank 2, Sensor 2 (or second o2 sensor back on bank 2) signal voltage is below what is considered normal for that sensor. It’s a four wire sensor being supplied a 0.5 volt reference voltage (usually on the signal wire) and a ground, as well as a power and ground circuit for the o2 sensor heater element. Changes in oxygen content cause resistance changes in the sensor’s signal circuit. This changing resistance affects the 0.5 volts on the signal/reference circuit. A heated o2 sensor is capable of switching between 0.1 volts and 0.9 volts. However, a properly working post-catalyst sensor will exhibit small changes at a slower rate than front (pre-catalyst) o2 sensors. It may switch slightly above and below 0.45 volts at the rate of about 1 switch per second or less(depends on the vehicle). The PCM monitors this changing signal to determine if the catalyst is working properly. If the PCM determines that the post-cat o2 sensor signal voltage is below a certain threshold for too long, P0157 Acura will set.

Symptoms

Possible sumptoms of OBD code P0157 Acura
Usually rear o2 sensor problems won’t cause drivability issues since they are an input that measures catalyst efficiency (unlike front o2 sensors). However if you have other codes present, like lean codes or pre-o2 sensor codes, then they may cause drivability problems as well as P0143 Acura. The following symptoms may be present: MIL (Malfunction Indicator Lamp) illumination Engine performance issues Engine running rough Engine running rich (only if PCM is trying to add fuel to compensate for low o2 sensor voltage reading) Engine running lean (only if vacuum leak is large enough that PCM can’t compensate by adding fuel) Poor idle

Causes

Possible causes of OBD code P0157 Acura
If you have reason to believe that your engine is running lean, fix that problem first, then clear codes and see if the P0157 Acura code resets. An engine that is running lean could set this code, but usually there will be lean codes (P0171 Acura, P0174 Acura) present. The following could be causes: Air leaks in exhaust in front of o2 sensor giving false reading Engine running excessively lean O2 sensor connector damaged/corroded O2 sensor signal circuit is shorted to ground O2 sensor ground circuit is open O2 sensor has failed (it may be contaminated with fuel or coolant) PCM has failed

Possible Solutions

It’s always good to start with checking for air leaks in the exhaust manifold and in the exhaust pipes. Fix these first. With KOER (Key on engine running) use a scan tool or a voltmeter check the o2 sensor signal voltage with engine warm. You may have to increase the RPM to a fast idle to check the voltage of the bank 2,2 sensor. If it’s voltage is stuck low (less than 0.5 volts may not be enough to set the code, but it depends on the vehicle) and you don’t have any other o2 sensor codes present in the PCM, then it’s a good bet that the sensor is bad. If the voltage isn’t stuck low and the o2 sensor seems to be operating fine, it’s likely sticking low intermittently. This often turns out to be the sensor. In either case, replacing the sensor can be an effective way to diagnose the problem. But it can also be an expensive diagnostic tool, especially if it turns out to be a wiring issue, instead of a sensor. So, if you’re interested in knowing for sure what the problem is before spending unnecessarily, then perform the following: 1. Turn off the engine and unplug the 2,2 o2 sensor connector. Inspect for corrosion, etc. Repair as necessary. Make sure that there is battery voltage present and ground present for the o2 sensor heater. If there isn’t, then diagnose that first then retest. The o2 sensor depends on the heater to warm it up so it can start working quicker. If the heater element is bad or there isn’t the proper voltage supplying it, the sensor may set this code. Usually heater problems have codes associated with them, too. If you find there is no battery voltage feeding the o2 sensor use the associated code to diagnose that. If you find the heater element bad, replace the sensor. If the heater element checks out then, using a jumper wire, supply a chassis ground to the o2 sensor connector(PCM side) ground circuit. Now observe the scan tool bank 2,2 o2 sensor reading. If it is now at about a half a volt then replace the o2 sensor. If, after supplying a ground to the unplugged PCM side of the o2 sensor connector, the voltage reading doesn’t change then check the harness for short to ground. Check for harness making contact with exhaust components. Check pins for damage, and for moisture. Repair as necessary. If you can find no harness problems, then the PCM may be at fault.

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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