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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
P0420 code
Honda has a technical service bulletin (TSB) out for this condition. There are 2 possibilities to correct this fault, according to the bulletin: Replace the catalytic converter Software update of the engine computer One last thing...
Question
p0420
A vehicle with 182,000 miles is likely due for a catalytic converter. Most of the time it does mean you need a new catalytic converter. But there are a couple of other things that are prudent to take a look...
Question
I have the P0420 code
Hi there, thanks for writing in. Code P0420 has to do with the catalytic converter in your vehicle. The code will need to be diagnosed by checking the vehicle for exhaust leaks, O2 sensor problems, or the wiring to the...
Question
Code p0420
Hello. P0420 could be due to a variety of faults including even a fuel pump that is not supplying sufficient fuel, causing a lean condition, and hence "fooling" the O2 sensors (pre and post) as to the status (i.e., efficiency)...
Question
Bad O2 sensor
Hello, code P0420 represents right main catalyst deterioration. There can be a few things that need to be checked before replacing parts. The intake system needs to be inspected for vacuum leaks and unmetered air leaks. The exhaust system should...
Question
code P0420 on my 2012 Chevy Equinox 2.4L O2 sensors
The code P0420 for your 2.4 L engine is for the after the catalyst O2 sensor. Your vehicle has only two O2 sensors. One is in manifold before the catalyst and the other is after the catalyst. The code can...
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...
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
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
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
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
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
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
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
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
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
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
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
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
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...

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