Check engine light code
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Senior User
Joined: Apr 2004
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Check engine light code
I have a 1996 F-150 4x4 5spd 302. The check engine light has been on for about 2 weeks and it went off once but came on and is still on. I pulled the codes and code 133 (O2 sensor circuit slow response (bank 1 sensor 1). Does this mean i need to replace one of the O2 sensors and if so which one. Any responses are appreciated. Thanks
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Joined: Sep 2004
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The sensors would be the ones closest to the engine (ahead of the catalyst). It isn't possible for sensors after the catalyst to get such a code (they will always be "slow" with a working catalyst due to the action of the catalyst). Code P0420 comes when the post catalyst sensor has a response similar to the pre-catalyst sensor.
I'm not sure whether bank 1 is the left side or the right side on a Ford. Personally, I'd change out the pre-catalyst sensors on both sides. They likely have similar amounts of age on them. Expected sensor lifetime is around 60000 miles, though they often go longer. A slow sensor will tend to degrade your gas mileage.
I'm not sure whether bank 1 is the left side or the right side on a Ford. Personally, I'd change out the pre-catalyst sensors on both sides. They likely have similar amounts of age on them. Expected sensor lifetime is around 60000 miles, though they often go longer. A slow sensor will tend to degrade your gas mileage.
