Hi all, first time posting here, long time reader. I've been helped out tremendously by honda-tech forums many times in the past.

I have a 2005 Honda Civic Value Package, with a 1.7L 4 Cyl, manual everything (besides transmission), and I have a problem that I just can't find a simple solution to.

A few days ago, I got in my car to head to work, and when I cranked the car and turned the A/C on, I noticed that it wasn't coming on. I also noticed that none of the lights pictured here running across the bottom were illuminating the way they're supposed to when the A/C or heater is turned on.

So, I of course immediately assumed the problem was either a blown fuse or bad relay, but after checking all possible fuses and relays (conventional jumper wire test) in both fuseboxes, all were fine. So, later that day, my check engine light came on, and I knew it must be from the A/C problem. I promptly took it to AutoZone to get a CEL readout of which codes were appearing, and I got a P0135:

A/F sensor 1 heater system malfunction
Probable causes:
-Open or short circuit condition
-Poor electrical connection
-Faulty A/F sensor 1

I've read that it could be the O2 sensor, but would that sensor being bad cause the lights across the dash to completely stop working as well?

Just confused! Any help is greatly appreciated!

 

Bump. Anybody?

 

Have you tried this?
What about testing the HVAC panel to see if it's getting power?


I also wouldn't rule out the MCU (multiplex control unit) but we'll start with the other stuff first.


Have you tried resetting the PCM to see whether or not the MIL and DTC were an intermittent problem?



Also, I recommend buying a service manual. Click Me
Item# 61S5C01