05 Civic EX code p0340 and p0344!
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05 Civic EX code p0340 and p0344!
OK so I read all about my error codes and replaced the Camshaft position sensor. A day later my engine light comes up again with a new error code of p0420 Catalyst system operating below threshold (bank1) bank 1.
I find it odd that as soon as I replaced my camshaft sensor the cat goes bad! Is there any way to test this before going through with replacing the cat.
Also I did a Seafoam treatment about 2 months ago. Of course after I do the treatment I read you should pull your O2 sensor before hand. Im curious if the O2 sensor could be throwing a bad code? Any suggestions are welcomed and appreciated.
Thank you
I find it odd that as soon as I replaced my camshaft sensor the cat goes bad! Is there any way to test this before going through with replacing the cat.
Also I did a Seafoam treatment about 2 months ago. Of course after I do the treatment I read you should pull your O2 sensor before hand. Im curious if the O2 sensor could be throwing a bad code? Any suggestions are welcomed and appreciated.
Thank you
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Re: 05 Civic EX code p0340 and p0344!
-Reset the ECM/PCM: With the ignition OFF, pull fuse #6 in the under-hood fusebox for at least 10 seconds.
-If the code comes back, crawl under the car and LIGHTLY tap the catalytic converter. If you hear stuff rattling around replace the cat. If you replace the cat I would recommend replacing the sensor also.
-If the code comes back and the cat doesn't rattle, replace the sensor
I would recommend OEM for either the cat or sensors, these Hondas can be finicky about that stuff. Unfortunately both the cat and the sensors for your model are expensive. This is about as cheap as it gets: https://www.hondapartscheap.com/inde...%20-%20MUFFLER
-If the code comes back, crawl under the car and LIGHTLY tap the catalytic converter. If you hear stuff rattling around replace the cat. If you replace the cat I would recommend replacing the sensor also.
-If the code comes back and the cat doesn't rattle, replace the sensor
I would recommend OEM for either the cat or sensors, these Hondas can be finicky about that stuff. Unfortunately both the cat and the sensors for your model are expensive. This is about as cheap as it gets: https://www.hondapartscheap.com/inde...%20-%20MUFFLER
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How's the car running?
Giving your cars age I would tend to think the seafoam treatment may have messed up one (or both) of the O2 sensors. Cat's generally last about 10 years if not longer, I got 13 years out of my old Civic.
If the car was only driven short distances for most of its life then it is possible for the cat to be bad already, they like to be hot.
OEM cats/O2 sensors are expensive but it's the only way to go, the aftermarket ones are junk and you'd be lucky to get a year of poor MPG and constant CEL's.
Giving your cars age I would tend to think the seafoam treatment may have messed up one (or both) of the O2 sensors. Cat's generally last about 10 years if not longer, I got 13 years out of my old Civic.
If the car was only driven short distances for most of its life then it is possible for the cat to be bad already, they like to be hot.
OEM cats/O2 sensors are expensive but it's the only way to go, the aftermarket ones are junk and you'd be lucky to get a year of poor MPG and constant CEL's.
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How's the car running?
Giving your cars age I would tend to think the seafoam treatment may have messed up one (or both) of the O2 sensors. Cat's generally last about 10 years if not longer, I got 13 years out of my old Civic.
If the car was only driven short distances for most of its life then it is possible for the cat to be bad already, they like to be hot.
OEM cats/O2 sensors are expensive but it's the only way to go, the aftermarket ones are junk and you'd be lucky to get a year of poor MPG and constant CEL's.
Giving your cars age I would tend to think the seafoam treatment may have messed up one (or both) of the O2 sensors. Cat's generally last about 10 years if not longer, I got 13 years out of my old Civic.
If the car was only driven short distances for most of its life then it is possible for the cat to be bad already, they like to be hot.
OEM cats/O2 sensors are expensive but it's the only way to go, the aftermarket ones are junk and you'd be lucky to get a year of poor MPG and constant CEL's.
I am going to try the suggestions lazlong posted and go from there. I hope I dont hear the dreaded Cat rattle ($825.53)
haha Thank you both for your posts!
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Re: 05 Civic EX code p0340 and p0344! -Reset the ECM/PCM: With the ignition OFF, pull fuse #6 in the under-hood fusebox for at least 10 seconds.
-If the code comes back, crawl under the car and LIGHTLY tap the catalytic converter. If you hear stuff rattling around replace the cat. If you replace the cat I would recommend replacing the sensor also.
-If the code comes back and the cat doesn't rattle, replace the sensor
I would recommend OEM for either the cat or sensors, these Hondas can be finicky about that stuff. Unfortunately both the cat and the sensors for your model are expensive. This is about as cheap as it gets: https://www.hondapartscheap.com/inde...%20-%20MUFFLER
-If the code comes back, crawl under the car and LIGHTLY tap the catalytic converter. If you hear stuff rattling around replace the cat. If you replace the cat I would recommend replacing the sensor also.
-If the code comes back and the cat doesn't rattle, replace the sensor
I would recommend OEM for either the cat or sensors, these Hondas can be finicky about that stuff. Unfortunately both the cat and the sensors for your model are expensive. This is about as cheap as it gets: https://www.hondapartscheap.com/inde...%20-%20MUFFLER
Looked at O2 sensors with scan tool: Downstream O2 seems to show correct waveform and voltage, but Upstream O2 shows a relatively "flat-line" voltage of about 0.98 V. Disconnecting Upstream O2 doesn't seem to affect current engine performance, and forcing "lean" and "rich" situations doesn't seem to affect the Upstream O2's waveform.
Question: Does the 2005 CivicLX use a Wideband/Lambda, or a "binary transition" style, in its Upstream O2 sensing routine? Any trouble-shooting suggestions (other than to just replace the Upstream O2 - too expensive) will be appreciated. Thanks.
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It is an A/F sensor. An A/F Ratio sensor does not operate the same way as a regular O2 sensor.
Looks similar, similar duties, but doesn't operate anything like an O2 sensor.
You cannot judge what is happening there based on what you knew about O2 sensors.
It should be pretty darn steady until you hit "decel fuel shutoff", then you should see how it indicates an extremely lean condition.
Wait a sec....
Actually, I'm not sure about that now that I think about it.
You have some generic scanner??
My HDS reads those in milliamps, not volts.
I can see the milliamps fluctuate as it keeps up with fueling changes.
Volts is not part of the front sensor equation on my scanner.
Anyway....
You can stare at the rear O2. If it swings a lot, the cat is probably suspect.
That isn't really good judgement though.
We don't know what the thresholds are that the PCM uses to judge the cat.
But you can trust the PCM.
It thinks the cat is bad.
If there aren't any manifold exhaust leaks before the cat, and no leaks within a couple feet after the cat.... I'd trust the computer.
HTH
Looks similar, similar duties, but doesn't operate anything like an O2 sensor.
You cannot judge what is happening there based on what you knew about O2 sensors.
It should be pretty darn steady until you hit "decel fuel shutoff", then you should see how it indicates an extremely lean condition.
Wait a sec....
Actually, I'm not sure about that now that I think about it.
You have some generic scanner??
My HDS reads those in milliamps, not volts.
I can see the milliamps fluctuate as it keeps up with fueling changes.
Volts is not part of the front sensor equation on my scanner.
Anyway....
You can stare at the rear O2. If it swings a lot, the cat is probably suspect.
That isn't really good judgement though.
We don't know what the thresholds are that the PCM uses to judge the cat.
But you can trust the PCM.
It thinks the cat is bad.
If there aren't any manifold exhaust leaks before the cat, and no leaks within a couple feet after the cat.... I'd trust the computer.
HTH
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Re: 05 Civic EX code p0340 and p0344! It is an A/F sensor. An A/F Ratio sensor does not operate the same way as a regular O2 sensor.
Looks similar, similar duties, but doesn't operate anything like an O2 sensor.
You cannot judge what is happening there based on what you knew about O2 sensors.
It should be pretty darn steady until you hit "decel fuel shutoff", then you should see how it indicates an extremely lean condition.
Wait a sec....
Actually, I'm not sure about that now that I think about it.
You have some generic scanner??
My HDS reads those in milliamps, not volts.
I can see the milliamps fluctuate as it keeps up with fueling changes.
Volts is not part of the front sensor equation on my scanner.
Anyway....
You can stare at the rear O2. If it swings a lot, the cat is probably suspect.
That isn't really good judgement though.
We don't know what the thresholds are that the PCM uses to judge the cat.
But you can trust the PCM.
It thinks the cat is bad.
If there aren't any manifold exhaust leaks before the cat, and no leaks within a couple feet after the cat.... I'd trust the computer.
HTH
Looks similar, similar duties, but doesn't operate anything like an O2 sensor.
You cannot judge what is happening there based on what you knew about O2 sensors.
It should be pretty darn steady until you hit "decel fuel shutoff", then you should see how it indicates an extremely lean condition.
Wait a sec....
Actually, I'm not sure about that now that I think about it.
You have some generic scanner??
My HDS reads those in milliamps, not volts.
I can see the milliamps fluctuate as it keeps up with fueling changes.
Volts is not part of the front sensor equation on my scanner.
Anyway....
You can stare at the rear O2. If it swings a lot, the cat is probably suspect.
That isn't really good judgement though.
We don't know what the thresholds are that the PCM uses to judge the cat.
But you can trust the PCM.
It thinks the cat is bad.
If there aren't any manifold exhaust leaks before the cat, and no leaks within a couple feet after the cat.... I'd trust the computer.
HTH
If you think a good mechanic is expensive, try hiring a bad one
Joined: Dec 2011
Posts: 32,017
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From: Midwest. Aiming about mid-chest
Rep Power: 517 Re: 05 Civic EX code p0340 and p0344!
I guess I have never worked with that software, so I can't really comment on it....
The .98 - 1.00 could be representing a Lambda calculation.
The .98 - 1.00 could be representing a Lambda calculation.
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