greeen ranger

so every where I look it tells me to remove the 7.5 back up fuse in the under the hood fuse box. I removed it 3 times for atleast 3 minutes 2/3 times. i repeated the process because my CEL stayed on, plus my radio stations did not erase so i am starting to wonder why this is happening if the back up fuse is suppose to reset the CEL and erase the pre-setted radio stations. the third time i removed the fuse was for more than ten minutes, put it back in and as i expected no change in CEL nor radio stations being erased. anybody experience this before? and what's another way to reset the CEL?

Former User

What car?

Are you sure it's the Back Up fuse you removed? If so, your radio may have been rewired to a different constant voltage source.

As for the CEL, what code is thrown? If the underlying problem of the CEL was not fixed, the CEL code may be immediately thrown when the key is turned to ON(II) after resetting the ECU.

greeen ranger

yes, positive it is the back up fuse. I did have a new radio installed, but i didnt think that would change the fact that it wont erase the stations. It's 99 civic DX and i had bought a new 7.5 fuse because the previous one was blown. I've had 3 codes thrown: p1381, p1509, p0135. 0135 was the o2 sensor which i had replaced, drove ten miles and used a buddy's ob2 code reader and the code was still thrown for the o2 sensor. I did some research and supposedly it may take up to 100 miles for the code to begone.

Former User

All your codes are electrical and would be thrown almost instantly if not fixed.

You have 2 O2 sensors and P0135 is for the primary one. Did you replace the right one? In addition, P0135 can also be thrown by a bad O2 sensor wire, a blown fuse (#15), or even a bad ECU, so you may not have fixed the problem.

Check whether your radio is wired to get constant voltage on the Wht/Blu wire.

greeen ranger

Yea i replaced the primary one, which is on the exhaust manifold and which fuse #15, under hood box or under dash fuses?

Former User

The FAQs sticky has nice fuse box diagrams - it's a dash fuse.

greeen ranger

how do i find out if my ECU is not functioning correctly? as in like u said earlier, it could be the ECU