Ninety7Cex

I've been searching and didn't find any helpful info on the ex model after installing header off ebay for 50 bucks. I'm a welder The manifold was cracked, I thought I'd benefit by adding header gaining a few more hp. After installing the header and checking the CEL at advance auto parts, I get 2 codes p0141 heater element secondary sensor, and p1508 idle air control valve circuit malfunction something. Why would I get those codes after installing a new header with a new denso 02 primary sensor?? I probably wouldn't have got the codes if I welded the oem manifold??

Ninety7Cex

97 ex sedan 5 speed manual

Marvin1985

iTrader: (5)

Where in the header is the O2 sensor installed and did you make sure the clip is connected all the way in the harness?

Ninety7Cex

Its installed in the upper part of the header the same place it'd be installed on the oem manifold. On the 2nd part of the header which connects to the cat there was a hex head 3/4 bolt a plug I believe if you remove it you put a 02 sensor there but I didn't I left the plug in. The secondary 02 sensor is installed after the cat and hasn't been touched. Yes the clip is connected all the way in the harness or it'd throw a code for the primary sensor I believe

Marvin1985

iTrader: (5)

Try resetting the codes and see what comes back on.

Ninety7Cex

I kept the positive terminal of battery disconnected for 5 mins, codes still came back

Ninety7Cex

Doesn't make sense to pull those 2 codes on a ex after a header install? Is the header messing with the idle air control and secondary sensor?

B serious

iTrader: (1)

You probably rubbed thru one of the wires on the O2 sensor because you were moving things around. Are your lights pulsing?

Check the wiring on the secondary O2 sensor and on the wire harness plugs under the intake manifold. Check fuse #15 in the dashboard fuse box.

Google "fuse 15" and you'll find some similar info.

Ninety7Cex

I'll be able to check the wiring inside the car on the secondary 02 sensor tomorrow, it plugs into the cat. the old primary sensor read 9 ohms the new one is 18 ohms, would that have caused codes? I also pulled the back up 7.5 fuse under hood, cel came back on, fuse 15 under dash is good.

Judge Owens

Do you instantly get a light, or do you get it after your car warms up?

You said you installed a new o2 sensor, did it come with a diagram to wire it in? I assume it came with a plug to snap into your stock harness with no wiring involved,,,.

I had an issue like this in my old prelude with 2 of the black heater wires swapped around or something like that..

Ninety7Cex

Instantly get CEL. No wiring it plugged secure into stock harness. No code for primary sensor. Secondary sensor and iac was never touched before nor after the header install. Today I did disconnect the iac and reconnect, same code after reconnect.