P0420 intermittent
#1
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 P0420 intermittent
Seemed to me my 01 LX 5sp (177k miles) has been running normally. I hadn't driven it for a couple of days.
Monday: we had a lot of rain when I drove again to work. After about 10 miles of driving the CEL appeared... but the car seemed to be running fine to me, no hiccups.
Tuesday: I stopped by the Danger Zone and used the code reader. Cleared the code and when I got home I took a look at the down stream o2 sensor. All seemed normal. On the way home I ran the engine up to 4500 rpm in 2nd and it pulled strong and smooth.
Wed: Driving home and sitting in a long line of traffic at idle the engine started to struggle and seemed very slow to respond to throttle input. The CEL came back on 30 seconds later. I was worried it was going to cut off on me, but the idle smoothed out!
The engine sounded better and the car seemed to have more pep than its had lately!
Thurs: The CEL is still on but it's still running great. More fun to drive.
I hope the CAT isn't bad and this was a moisture issue with a o2 sensor connector. If the CEL doesn't clear itself I'll go back to the DZ and see what the code is and clear it again.
I've no interest in replacing parts or spending money when it is running smooth and has power. I don't normally rev it past 3k and I'm still getting 33-34 mpg on the winter blend.
If the only code is p0420, it indicates what? I'm not getting a code for an o2 sensor or anything else. No strange smells...
#2
If you think a good mechanic is expensive, try hiring a bad one
Re: P0420 intermittent
If the only code is p0420, it indicates what?
It does not automatically mean it has clogged or become a restriction.
Assuming it's not a false positive.
at idle the engine started to struggle and seemed very slow to respond to throttle input. The CEL came back on 30 seconds later. I was worried it was going to cut off on me, but the idle smoothed out!
#3
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
The basic meaning is the cat has lost efficiency. It's substrate has lost a significant portion of its ability to store and release Oxygen.
It does not automatically mean it has clogged or become a restriction.
Assuming it's not a false positive.
Does this happen with any frequency? If it did not set a code for sensors or fuel trims---only reset the cat code, I'd be interested in using a good scanner to graph out the o2 sensors and fuel trims while this event occurs.
It does not automatically mean it has clogged or become a restriction.
Assuming it's not a false positive.
Does this happen with any frequency? If it did not set a code for sensors or fuel trims---only reset the cat code, I'd be interested in using a good scanner to graph out the o2 sensors and fuel trims while this event occurs.
I've had the car almost 2 years. No temp issues, only CELs have been CPS sensor (Feb 2015) & primary o2 sensor (Oct 2014).
#5
If you think a good mechanic is expensive, try hiring a bad one
#6
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
On my way home from work the CEL cleared!
Its still running great, no engine hiccups.
I'll wait and see when it comes back, but I'm in no hurry to spend money, especially when its running good.
Its still running great, no engine hiccups.
I'll wait and see when it comes back, but I'm in no hurry to spend money, especially when its running good.
#7
Re: P0420 intermittent
When the cat become less efficient it does not affect the driving in any way.
Pull away the O2 sensor using Modified non fouler or build a circuit
Google p0420 fix
Last edited by emich; 02-23-2016 at 05:50 PM.
#8
OF top 99.5% creator (Formerly of the Puffinblunts variety)
#9
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
When the cat become less efficient it does not affect the driving in any way.
Pull away the O2 sensor using Modified non fouler or build a circuit
Google p0420 fix
$3 O2 simulator fix for P0420 Check Engine Light - YouTube
Pull away the O2 sensor using Modified non fouler or build a circuit
Google p0420 fix
$3 O2 simulator fix for P0420 Check Engine Light - YouTube
#10
#11
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
UPDATE:
The P0420 has tripped the CEL 1 more times since my original post.
So I bought the resistor and capacitor to add a low pass filter to my secondary o2 sensor.
I will take some pictures when I get it wired up.
The components cost me $2.83.
The P0420 has tripped the CEL 1 more times since my original post.
So I bought the resistor and capacitor to add a low pass filter to my secondary o2 sensor.
I will take some pictures when I get it wired up.
The components cost me $2.83.
#12
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
Hopefully no more CEL!
Last edited by bsmiley; 03-02-2016 at 06:04 PM.
#13
Registered!!
Thread Starter
Join Date: Apr 2014
Location: Hampton Roads, Virginia
Posts: 373
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 127 Re: P0420 intermittent
Please note the low pass filter will not work if you do not have a catalytic converter that is functioning.
Thread
Thread Starter
Honda Civic Forum
Replies
Last Post
Nick2618
Mechanical Problems/Vehicle Issues and Fix-it Forum
0
06-11-2012 08:13 AM
got2run5
Mechanical Problems/Vehicle Issues and Fix-it Forum
2
02-02-2012 10:30 PM
02civicboy
Mechanical Problems/Vehicle Issues and Fix-it Forum
0
12-10-2011 01:40 PM
ricerchick
Mechanical Problems/Vehicle Issues and Fix-it Forum
7
10-18-2011 01:11 PM
civicsrcool
Mechanical Problems/Vehicle Issues and Fix-it Forum
2
05-11-2008 10:16 PM