P0420 Catalyst System Low Efficiency
i just roled over 107,000 miles on my 2.4L 96 cavalier and i changed out only the upstream o2 sensor with a bosch sensor. and today i started to get engine code P0420. what does this mean? thanks.
~1996 Cavalier LS 2.4L (auto)
hmm... I've got the same code being thrown but I haven't changed the o2 sensor.. think I need to.
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- putting the pieces back together -
Letxen3 wrote:P0420 Catalyst System Low Efficiency
i just roled over 107,000 miles on my 2.4L 96 cavalier and i changed out only the upstream o2 sensor with a bosch sensor. and today i started to get engine code P0420. what does this mean? thanks.
you should have gotten one from the dealership. bosch o2 sensors are junk. however, this has no bearing on the downstream sensor, which is what sets the low efficiency code. either a: you need a new downstream o2, or b: your catalytic converter isn't working as well as it should, and needs to be replaced.
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cats are expensive like $250...i will try the cheap way 1st getting a new downstream o2 for $86.
what makes you say bosch sensors are bad?
~1996 Cavalier LS 2.4L (auto)
I thought the downstream o2 worked by looking at the air after the cat and the computer looked at the differential in value between the 2 sensors.
Do the cheap way and do it right, get a good upstream sensor. Return the Bosch and say it's faulty or something.
THEN if it doesn't work, buy a high flow cat. Or live with the CEL.
Letxen3 wrote:
what makes you say bosch sensors are bad?
Plain and simply, I sell them, and know the failure rates first hand.
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You might try just waiting a while and see if the problem persists. The way the two sensors' readings interact is a function of what's called a delta relationship, and it is adaptable to some degree in the PCM. It may need to fully adapt to the slightly different characteristics of the new upstream sensor.
Bill Hahn Jr.
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Rich Grayo Jr. wrote:Letxen3 wrote:
what makes you say bosch sensors are bad?
Plain and simply, I sell them, and know the failure rates first hand.
whats a good brand then to get...is it denso?
~1996 Cavalier LS 2.4L (auto)
Bill Hahn Jr. wrote:You might try just waiting a while and see if the problem persists. The way the two sensors' readings interact is a function of what's called a delta relationship, and it is adaptable to some degree in the PCM. It may need to fully adapt to the slightly different characteristics of the new upstream sensor.
interesting so this morning on my trip to miam 60 miles i had the light come on and i erased it about 5 maybe 6 times. well on my way back up north to west palm beach this evening the engine light did not come on.
i did also noticed this morning and at night when i started the car the rpms would make a sudden quick jump from 1000 rpms to about 1700 rpms. i have an automatic by the way, it just werid cuz it never did that before. it would jump myabe 2 times and then it settles and goes away once you drive off.
~1996 Cavalier LS 2.4L (auto)
someone meantions that the reason my bosch upstream o2 sensor may need warming up before it starts to read good. like i said on cold starts it will make idle jumpy and then goes away once you drive away.
~1996 Cavalier LS 2.4L (auto)
today i got this code come up again, i reset it and will see what happens.
~1996 Cavalier LS 2.4L (auto)
I just replaced both of my O2 sensors with NTK brand. Its been over 400 km's already things are working well. I had bosch before they are garbage.
