so i got some CEL codes pulled off my 99 civic si
1.BBA/F sensor 1 heater system malfunction
2.BBsecondary H02s12 circuit heater circuit malfunction
3. BBElectric load detector(ELD) circuithigh input

the guy at the store said my ECU may be bad but i dont know.
what do all these mean and how can i test my ECU to tell if its bad?
Which should i start with to see if they take the other problem away?

 

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If fuse 15 under the dash is blown, click here.

 

fuse 15 is fine

 

⇑

 

Does the speedometer work?

 

yes

 

If you clear the ECU by removing the BACKUP fuse under the hood for a couple of minutes and then drive the car, do all three codes repeat?

 

im not sure il try to test that out and see. which fuse is it?

 

The fuse labeled Backup under the hood.

 

all i see is this one. says backup(radio)

 

That's the one.

FYI -- You'll need to reset your clock and radio stations after clearing the ECU.

 

lol its cool i have to get that setup as well. so il do that then il get back to u.

 

any recommended amount of minutes to wait and minutes to drive? what code should this be testing out?

 

Removing the fuse for 2 minutes should be enough to clear the ECU codes. Afterward, drive the car for 15 minutes or so to see whether the CEL stays on while driving. If so, pull the CEL codes again yourself as described here. You are trying to determine whether any of the codes you posted earlier repeat. You should only troubleshoot codes that repeat. If the CEL does not stay on after clearing the codes and driving, then you may be good to go.

 

alllllrighty

 

alright. all the CELs went away but the o2 sensor cell. i guess il just have to replace those. thanks alot man.

 

Does one or both O2 sensor codes remain? Which one?

 

i believe it was this one BBsecondary H02s12 circuit heater circuit malfunction

 

That's the secondary O2 sensor plugged into the rear, top of the cat. Check the wires for damage before you replace. I hope that P0420 doesn't pop up after the you fix the secondary sensor because this could mean that the cat is bad.

 

me to. how much does a cat go for?

 

Suffice it to say that you don't want to throw a cat code.