I drive a 1999 Civic Si, ever since i put my header, new oem cat and 2.5'' catback exhaust ive had a check engine on showing codes PO135 and PO141
PO1352 Heater Circuit <Bank 1, Sensor 1>
PO141 o2 Heater Circuit <Bank 1, Sensor 2>
I put a new o2 sensor in both spots and still no change. now im stuck ive checked grounds, and fuses.

i rented a fuel pressure checker from autozone and my fuel before the fuel rail was around 35-37 psi and jumped slightly when i gave it gas, i hooked the tester up to the fuel pressure regulator and it did not show and reading at an idle or when i gave it gas, the filter ion the fuel rail is clean, so my question is, is my fuel pressure regulator bad and making my car run lean somehow? its not blowing black smoke so i know its not running rich. i dont know if i should spend the money on a new regulator or not. an experts advice would be very much appreciated.

 

Check fuse 15.

 

I checked the fuses, and fuel pressure and both fine. today i put a new fuel pressre regulator on and it remove code: po141 but po135 is still there. any suggestions?

 

Did you check installed 7.5A fuse 15 for voltage on both top test tabs?

 

just went thru same prob with my d16y7 check ecu

 

goldenchild707 did you have to replace the whole ecu?

i out my stock exhaust manifold back on today because the 02 bung on my header had a crack all the way around the weld so i figured that was it, and still nothing different p0135 still there. im going to get an ohms reader and check the output.

 

the fuse in 15 is good, i evn replaced it just to do it and still nothing.

 

One problem with just replacing a fuse is that you don't know whether it just immediately blows again. Voltage testing is the sure way to know. When you turn the key from off to ON(II), does the battery/charge light in the cluster turn on?

 

i need to get my hands ona voltage meter i dont have one, and yes the charge battery light comes on for a few seconds with the other lights then they turn off like normal.

 

btw i really appreciate the consistent replies im not getting to many straight forward answers from anyone else.