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P0420 Code Question
A couple of weeks ago the MIL lit up. When I checked the code it was a P0133 (O2 sensor, Bank 1). I replaced the O2 sensor, but now I have an intermittent P0420 code. Does anyone know if the two are related and if there is something causing it other than the worst possible located Bank 1 catalytic converter?
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Yes sometimes you need to replace both o2 sensors on that bank one. If it comes back you have 2 options
1 buy a new cat or a used one 2 buy o2 sensor extenders(not legal) let me know if you need a used one thanks, The Dr |
kitty wants a joint |
Thanks. I have a downstream sensor on order. The new upstream was a no name brand. Seems to be working fine, but I’ve read that the cheap ones can be squirrely. Could that be the cause? |
Update: the light went off then back on again. I tried to change the downstream O2 sensor, but couldn’t get it to budge, despite using two different O2 sockets. Will have a mechanic break it loose as soon as I have a chance. |
xjagRI: When an O2 sensor won't budge, an alternative is to cut the wires close to the sensor and use a deep 6 point socket, which grips the sensor better than the slotted sensor socket.
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+1
exactly what I needed to do |
Good tip. I’ll see if I can maneuver on into that space before I cut the wires. It’s a tight spot. |
remember to use a good penetrating spray the day before...something like PB Blaster....not wd40 |
are you sure the o2 sensor is bad did you test it
In your case, the P0420 code stands for “Catalyst System Efficiency Below Threshold (Bank 1).” When you receive a P0420 code it means your catalytic converter is not operating at maximum efficiency. Usually this means your catalytic converter needs to be replaced or there is a problem with your O2 (oxygen) sensors. |
This worked for me
I had the same problem on my car. This is what I used.
I think my problem was all bad threads on the pipes so I had to use them (cough cough) Ya that was the problem (cough caugh) bad threads...honest! |
if its a cat issue.... there are several cat cleaners on the market such as cataclean. according to reviews....they seem ro often work and ive seen some people remove the upstream o2 sensor, pour in seafoam. replace sensor and take a ride |
Latest Update: MIL went off then on again, so I checked the codes again. This time I had a P0305 and P1316 in addition to the P0420. So here is what I think is happening: 1. I have a misfire on #5 that has been happening, but finally threw a code. 2. P0305 code caused the car to throw a P1316 code. 3. The intermittent #5 misfire caused the O2 upstream sensor to fail (changed last month) and then the cat to become contaminated to the point is not working well. Which caused the P0420 code. Does that sound reasonable? Since I bought the car I have smelled burning oil when it is stopped at a traffic light or at idle. I’m thinking I have a valve (cam) cover gasket failure that fouled the #5 plug at the heart of all this. Hopefully the cat is not too far gone that it can’t be saved. Today I ordered new valve cover gaskets, coils, plugs, upper and lower intake gaskets. I won’t have time to do the work for a couple of weeks. Interested in what y’all think about my theory. |
when was yhe last time the plugs where changed
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Not sure. I just bought it a few months ago. |
seems a lot of us get a cyl 5 misfire...usually caused by a bad coil. |
Originally Posted by iownme
(Post 1949944)
seems a lot of us get a cyl 5 misfire...usually caused by a bad coil. |
Originally Posted by xjagRI
(Post 1949167)
Latest Update: MIL went off then on again, so I checked the codes again. This time I had a P0305 and P1316 in addition to the P0420. So here is what I think is happening: 1. I have a misfire on #5 that has been happening, but finally threw a code. 2. P0305 code caused the car to throw a P1316 code. 3. The intermittent #5 misfire caused the O2 upstream sensor to fail (changed last month) and then the cat to become contaminated to the point is not working well. Which caused the P0420 code. Does that sound reasonable? Since I bought the car I have smelled burning oil when it is stopped at a traffic light or at idle. I’m thinking I have a valve (cam) cover gasket failure that fouled the #5 plug at the heart of all this. Hopefully the cat is not too far gone that it can’t be saved. Today I ordered new valve cover gaskets, coils, plugs, upper and lower intake gaskets. I won’t have time to do the work for a couple of weeks. Interested in what y’all think about my theory. |
Thanks, I replaced the IMT gaskets with the OEM green ones a month ago. |
clyons, I, too think I’ll find oil in the plug well. Will let you know. |
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