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Discussion Starter #1 (Edited)
MY 2008 2DR CIVIC IS THROWING CEL P0135 LOW VOLTAGE TO THE O2 HEATER CIRCUIT. I HAVE CHECKED POWER TO FUSE 11, POWER TO PGM FI SUBRELAY (BOTH SIDES ) ALL HAVE 12 VOLTS BUT STILL NO POWER TO THE BLK/WHT WIRE ON THE 02 SENSOR (A/F 1). I HAVE OHM CHECKED THE BLK/WHITE WIRE TO THE PURPLE WIRE AT THE FUSE BOX. IT CHECKS GOOD WITH .2 OHMS. I BELIEVE THE PROBLEM IS THE GROUND SIDE OF THE PGM FI SUB RELAY (RELAY SIDE) CAUSING THE RELAY NOT TO LATCH BUT I DONT KNOW WHERE THE GROUND FOR THIS RELAY IS.
IVE BEEN USING THE WIRE DIAGRAM AT THIS LINK.
Wiring Diagram

ALSO OUT OF COURIOUSITY WHAT OTHER CIRCUITS GO THROUGH THIS RELAY? ANY IDEAS?
 

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What if any mods do you have on your car? Sounds like you been f#cking with the 02 sensors.
 

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Double check any mods you have done first, they will be the most likely cause.

Have you had the PGM disconnected at anytime? If so, pull the connectors off again and double check for bent pins.

Try removing the O2 sensor, start the car, and check for battery voltage where PUR WHT/BLK wire meet. If you get a reading there then that means your relay is working and the problem is most likely with the O2 sensor, or it's connections.

Good luck..
 

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MY 2008 2DR CIVIC IS THROWING CEL P0135 LOW VOLTAGE TO THE O2 HEATER CIRCUIT. I HAVE CHECKED POWER TO FUSE 11, POWER TO PGM FI SUBRELAY (BOTH SIDES ) ALL HAVE 12 VOLTS BUT STILL NO POWER TO THE BLK/WHT WIRE ON THE 02 SENSOR (A/F 1). I HAVE OHM CHECKED THE BLK/WHITE WIRE TO THE PURPLE WIRE AT THE FUSE BOX. IT CHECKS GOOD WITH .2 OHMS. I BELIEVE THE PROBLEM IS THE GROUND SIDE OF THE PGM FI SUB RELAY (RELAY SIDE) CAUSING THE RELAY NOT TO LATCH BUT I DONT KNOW WHERE THE GROUND FOR THIS RELAY IS.
IVE BEEN USING THE WIRE DIAGRAM AT THIS LINK.
Wiring Diagram

ALSO OUT OF COURIOUSITY WHAT OTHER CIRCUITS GO THROUGH THIS RELAY? ANY IDEAS?
Turn off your CAPS!:facepalm:
 

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Ok my drawing are simular but not exactly the same as your link. Here is what I have on my drawing for a 2007 civic R18.
The ground side of the PGM-FI Sub relay coil ( relay pin 3 ) makes its ground through the PCM. On my schematics relay pin 3 goes to connector F16 of the fuse box, then goes to pin A21 of the PCM. The wire color is shown as LT Blue ( or Pink )
As far as load on the contact side of the relay I see the following: 1) A/C condenser fan relay coil via fuse #15, 2) the evap canister vent valve 3) the primary O2 sensor heater circuit.
The ground side of the O2 sensor heater circuit is also through the PCM. It a green wire ending on pin C9 of the PCM.

Happy hunting !
 

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Discussion Starter #6
wow someone who understands the question awsome. I also had a evap canister vent valve code that i wasnt disclosing because i believed they were related and not two separate problems. So ill ring out the wiress tomorrow. where can i get a copy of the diagram your using? My email is [email protected]
also fyi when i jump pins 1 and 2 on the subrelay i get my 12v to the sensor. So i know its a ground issue with the subrelay and yes IVe changed it twice. thanks for the help.
 
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