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45837 posts · Joined 2007. #2 · May 17, 2020. @Jaime ochoa welcome to the forum from Oregon! The P0420 CEL code is from the rear O2 sensor, but that doesn't mean the sensor is bad. The rear O2 sensor is monitoring for excess 02 in the exhaust flow, so the fault could be something upstream... even a pinhole leak in the exhaust pipe?May 31, 2012 · 16442 posts · Joined 2015. #24 · Feb 24, 2017. Alright for future people who find this p0420 is a catalyst failure. You either need to replace the cat, replace the sensor if the cat is good, or ideally have the proper tune on the car so it blocks the code. Sent from my SAMSUNG-SM-G935A using Tapatalk. P0420 - Catalyst System Efficiency Below Threshold (Bank 1) P0031 - HO2S Heater Control Circuit Low (Bank 1 Sensor 1) ... but my view is the rear O2 sensor, which generates this code, is a poor after-thought by Subaru. The '$5 fix' reduces the sensitivity of the rear O2 sensor. It doesn't really 'fix' anything (except for the bleeping CEL light ;-)ETF strategy - SCHWAB FUNDAMENTAL U.S. BROAD MARKET INDEX ETF - Current price data, news, charts and performance Indices Commodities Currencies StocksThis is a very common Subaru code. It ranges from seemingly "unfixable" (i.e., reflash the ECU to ignore it), catalytic converter replacement, rear O2 sensor, exhaust leak, all kinds of stuff. I wouldn't worry too much unless other symptoms/codes appear. My car throws a P0420 about every 1000-2000 miles (edit: and still gets high 20's average ...It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model. So this engine code article applies to Nissan, Toyota, Chevrolet, Ford, Honda, GMC, Subaru, VW, etc. P0420 is one of the more common trouble codes that we see.The most common fix for P0420 in the Subaru Impreza is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Impreza into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Impreza: 1. Check for Other Codes.I ran into a code that occurred 3 times now when driving on the freeway only at around 60-70 mph which was a P0420 code. I have been told by fellow Subaru enthusiasts in my area to replace the front O2 sensor, but read on this forum that it should be the rear sensor. On the 2011 LGT, the O2 sensors are close to each other so I really …Using my cheap scanner I have a P0420 code "Catalyst System Efficiency below threshold". Some info I found pointed to these sensors: Mass Air Flow. Manifold Absolute Pressure. Engine Coolant Temperature. Air Fuel (upstream O2 Sensor) O2 (downstream O2 Sensor) Other info was to change the spark plugs, it is about time.Podcast episode breaking down myths about ADHD in both adults and children (Attention Deficit Hyperactivity Disorder) For some, ADHD is a debilitating disorder. For others, it’s se...There is a lot of info out there on this subject but none seemed to be specific to an intermittent power loss issue with P0420. I understood one sensor should fluctuate rapidly (upstream) and the other should remain fairly steady. If I recall correctly, the fluctuation was between about .04-.80.4 days, 1 subaru wideband sensor, and 3 drive cycles later, I have clearing subaru readiness monitors down to a T. And the wide-band that came with my AEM failsafe gauge is looks to be the same model as …December 27, 2022. Advertiser Disclosure. TABLE OF CONTENTS. Fix your check engine light yourself. GET FIXD. What Does Code P0420 Mean? P0420 definition : Catalyst …The P0420 code signals a low catalyst system efficiency. This code suggests that the oxygen levels are below the desired threshold (Bank 1), which most often results from problems with your car ...How to diagnose code P0420 on a Subaru Legacy. Typically, you'lGet ratings and reviews for the top 7 home warranty compan J. Jdave Discussion starter. 7 posts · Joined 2017. #11 · Sep 11, 2019. A code P0420 may mean that one or more of the following has happened: Leaded fuel was used where unleaded was called for (unlikely) A damaged or failed oxygen / O2 sensor Downstream oxygen sensor (HO2S) wiring damaged or connected improperly. Every mechanic has seen intermittent P0420's that come back af P0420 is catalyst below efficiency. P0303 is misfire on cylinder 3. The misfire could be contributing to the catalyst problem so it should be addressed first. Pull the # 3 plug and look for carbon or wet with gas. The old plug wires are also suspect. Clean the plug and re-install. Check the connections on both ends of the wire.PO420 code. Thanks for taking the time to help. I have a 2004 Outback 2.5L automatic. J259. Code P0420. I've replaced the bank 1 sensor 1 with a Denzo brand. I've ran 2 different cleaners through the gas tank. I got the car with a blown head but had it fixed. I replaced the sensor after the head was fixed. The P0420 Code in a Subaru WRX usually m

The most common fix for P0420 in the Subaru WRX is a new catalytic converter, followed by an O2 sensor replacement. Before taking your WRX into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru WRX: 1. Check for Other Codes.The most common fix for P0420 in the Subaru Baja is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Baja into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Baja: 1. Check for Other Codes.4 days, 1 subaru wideband sensor, and 3 drive cycles later, I have clearing subaru readiness monitors down to a T. And the wide-band that came with my AEM failsafe gauge is looks to be the same model as …P0420 is generally a universal code for Catalytic Converter limit below threshold or something along those lines. P0420 indicates a failing catalytic converter. ... A forum community dedicated to Subaru Impreza and STI owners and enthusiasts. Come join the discussion about performance, engine builds, exhaust, modifications, troubleshooting ...

45837 posts · Joined 2007. #2 · May 17, 2020. @Jaime ochoa welcome to the forum from Oregon! The P0420 CEL code is from the rear O2 sensor, but that doesn't mean the sensor is bad. The rear O2 sensor is monitoring for excess 02 in the exhaust flow, so the fault could be something upstream... even a pinhole leak in the exhaust pipe?The P0420 code is a common issue that many Subaru Impreza owners experience. This subheading aims to provide a detailed explanation of what the code means and its implications for the vehicle. The P0420 code signifies a problem with the catalytic converter efficiency in the exhaust system of the Subaru Impreza.…

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs. After a night in Nelson, we arrived in Revi for a few blue. Possible cause: I'm thinking it definately needs a tune up and some other minor maintenan.