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P0420

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P0420 OBD-II Trouble Code: Catalyst System Efficiency Below Threshold (Bank 1)
P0420 code means that either the upstream or downstream oxygen sensor in the catalytic converter is not working. Replacing these parts can fix P0420.

Related questions

Question
Catalyst system Efficiency - P0420 - 2010 Ford Fusion.
Hello and thank you for contacting Your Mechanic. For the code P0420 to come on, there could be a lot of issues that could arise to a non functioning catalytic converter. Before you decide to replace the catalytic converter, consider...
Question
Po420 bank1
Hello Tom. P0420 is the Catalyst System Efficiency Below Threshold (Bank 1) code. While there are a multitude of components that can cause this code, the general concept is that your catalytic converter is not working properly. If you suspect...
Question
P0420 code and engine is not starting.
Hi there. The p0420 code means that the catalytic converter is below threshold and is not functioning correctly. This code comes up when the catalytic converter can no longer burn off any fuel in the exhaust system. Take a raytech...
Question
P0420 P0430 trouble codes
Hello. Thanks for writing in. The universal oxygen sensors, a bad connection, or a bad catalytic converter can all be the cause of the codes. If you can you access to a known good oxygen sensor and test it in...
Question
I have a 06 Infiniti M45. The service engine light came on. Got the codes of p0420 and p0430. Wondering if I need to replace both O2 sensors.
Hi there. When the codes P0420 and P0430 come up, usually the catalytic converter has failed, but before you determine if you need to replace the catalytic converter, consider checking the following: A damaged or failed oxygen sensor on...
Question
Code P0420 shows on the dash of my 2005 Acura MDX
Acura did have a tech bulletin released in September 2011 regarding fault P0420 and a possible software update that may rectify this situation. You can try contacting your local Acura dealer service department or Acura Customer service to see if...
Question
05 Nissan Frontier has a code of p1283 and p0420. Why are these codes stored?
Hi there. The code p0420 is present for the O2 sensor behind the catalytic converter has detected the air fuel ratio is not within the limits. The code p1283 is present for the air fuel ratio sensor is registering a...
Question
I took my car to Advance Auto and them do a check engine light diagnostic test and the code is C0245
Hello. Thanks for writing in. You may have two separate issues going on at once. The speed sensor code is likely due to sensor failure, or a bad connection. In the case of a bad connection, a good visual inspection...
Question
2004 Nissan Altima- Won't move when the code reads p0420 on the scanner. Did my transmission go? Is it my catalytic converter like code said?
Hi there. The code P0420 means that the catalytic converter is below threshold and cannot burn off any emissions in the exhaust stream. The O2 sensors have pickup this fault and put the engine into limp mode. As for the...
Question
My car shows trouble codes P0133 and P0420
Hi there: It appears as if you've got a lot of miscommunication going on with your mechanic. Here are a few basics. First, anytime an error code is triggered, such as the P0133 OBD-II code the issue needs to be...
Question
My engine is about to kill itself.
If the vehicle transmission has entered limp mode and the engine is really misfiring, these faults have to be diagnosed separately. The engine misfiring should be dealt with first. Typically, the engine is scoped to look at secondary firing patterns...
Question
Code P0420. Need to replace catalytic converter.
Hi there. The code P0420 is coming up for the Downstream Oxygen sensor has picked up an abnormal reading and is saying that the catalytic converter is below threshold. There could be a misfire on the engine, leaking injector, ignition...
Question
After i full with gas I got code P0420
Hello, thank you for writing in. When there are issue with the vehicle's gas recirculation system, the engine may pull in excess exhaust fumes. This will cause the engine to run rich and make the catalytic converter unable to compensate...
Question
Check Engine light on the Dashboard.
Hi there. The code P0420 could have an issue with the following: Having a damaged or failed oxygen sensor The engine coolant temperature sensor is malfunctioning Damaged or leaking exhaust manifold or leaking muffler / catalytic converter The spark...
Question
Catalytic Converter Replacement - 2001 Lexus IS300.
Hi there. Before you decide to have the catalytic converter replaced in your vehicle, consider performing the following checks: Check the following: A damaged or failed oxygen sensor The oxygen sensor wiring damaged or connected improperly The engine coolant...
Question
Repeated Cat Code: P0420 keeps coming up.
Hi there. The code is coming up for more than the O2 sensors or Catalytic Converter. Perform the following steps to determine what is the cause for the code P0420. Check the following A damaged or failed oxygen sensor...
Question
My chevy venture is pulling up a po420 code but we can't seem to find out why ?
Diagnostic Trouble Code P0420 has many, many potential causes including a damaged muffler or leaks in the muffler, damaged exhaust manifold or leaks in the exhaust manifold, damaged exhaust pipe or exhaust pipe leaks, misfiring in the engine, oil contamination...
Question
My 2001 chevy venture shuts off on me at random times . A couple of days the check engine light was on so we hooked the computer u
It's not unusual for code P0420 to come on, stay on for even a few days, and then just disappear. Then, months later, it might happen again (i.e., appear and disappear). If this is the circumstances you face, I would...
Question
po420 code went on, what are chances that it is actually my catalytic converter
Hello, thank you for writing in. A catalytic converter going bad after this amount of mileage is not unheard of. Although you will definitely want to check the oxygen sensors first. If you are in a position to test them...
Question
I have a 2007 dodge charger v6 3.5L engine NAG1 RWD Transmission. I'm confused in what is causing limp mode in my car..when the c
The code P0420 will cause the computer to put the transmission in limp mode to protect the catalytic converter. Check the following areas to see the cause for the P0420 code condition: P0420 A damaged or failed oxygen sensor...

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