Car problems

  • Thread starter Thread starter cny85
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cny85

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Ok I posted on here a while back about an 02 sensor. When I bought the car they put 87 in it. The check engine light came on and it said my engine was misfiring, so I put octane booster in and it went away. A few weeks later I decided to try 89 This caused the check engine light to come on again saying this.

The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 indentifies the cylinders on the opposite bank).

I don't think my cat has gone bad its been on for a year. My gas mileage is around 20mpg and I don't notice the engine bogging down. I have replaced the 02 sensor b4 the cat on the passenger side. Does anyone have any other suggestions.
 
Cylinder Numbering

FWIW, please note that the cylinders are numbered 1,2,3,4 from the front to the fire wall on the passenger side and 5,6,7,8 on the driver's side. Ford has done it that way from the beginning of the V-8 back in 1932. Firing order is 1,5,4,2,6,3,7,8. You'll be aware that that means that the first side is the PASSENGER side and the lower numbered O2 Sensors will be found there. The higher numbers are the driver's side.
KS
 
idk being dumb I guess I thought if I mixed 93 and 89 I would get 91 and might save some money. I should have just spent the extra dollar. Yeah I replaced the bank 1 sensor 1 on the passenger side b4 the cat. I was wondering if anyone else might have had this problem, and had any advice for me.
 
It seems to me u need to replace 02 sensor #2 on the passenger side. The 02 sensors after the cats are the ones that monitors the cats efficiency. SO since its saying the cat on bank one (passenger side) is below threshold it means the cats basically not doing its job, or the sensor just isn't reading correctly...So i would guess its ur 02 sensor rather then your year old cat.
 
yeah thats what I was thinking. The cats not a year old. the light has been on a year, and I've had no problems.
 
i had the same exact error message on my 2000 LS and the CEL eventually went away. like you, i had no performance issues and it hasn't come back to haunt me (knock on wood). i just recently passed California smog check so obviously the cats hadn't failed. though i did barely pass - i think i was 2 points under the maximum amount allowed by law, hehe.

anyways, i asked this same question two years ago on the forum when this started with me, and most people felt it was unusual that the 02 sensors fail like this, and felt it was the cat or something further upstream. replacing the 02's might turn the CEL off, but they might not, because it could be something else tripping them and they ARE doing their job. hard to tell, i just gave up and lived with it and the CEL is off so its all good :D
 
Yeah I might end up replacing the other sensor. I'm just wanting to sell the car and with a check engine like on it will be harder to sell.
 
what was the actual code?

"catalyst system efficiency" usually means the reading between the front and rear O2 sensor was not enough - meaning the PCM thinks the CAT is not cleaning the exhuast enough. If it's not your CAT then it is likely either or both O2 sensors.....

Clear the code. See if it comes back. If it does, sway the O2 sensor you did not replace with the one from the other side, clear the code

if the code reports on the other side - then you know you have a bad O2 sensor
if the code still reports on the same side - likely the CAT
 
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