1998 Honda Odyssey

Electrical problem
1998 Honda Odyssey 4 cyl Front Wheel Drive Automatic 130000 miles

This is basically the same engine as a 1998 honda accord. I had the check engine light come on and Autozone told me it was a P0135 and that I needed a new oxygen sensor. I purchased a Bosch direct fit and had it in without trouble. But. The check engine light remained. I took it to Autozone to have them clear it to no avail. It came right back on. I went home and double checked everything. No loose or burnt wires. Connector snapped on tightly.

Googling the code, I've come to realize that the code is specifically for " Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)". This vehicle only has two O2 sensors and I verified that I had in fact replaced the one before the Cat.

This leads me to believe that the problem is in the circuit away from the O2 sensor. I know that there is a relay that provides power to the O2 sensor but it also provides power to the other O2 sensor and a couple of other sensors.

I might check for voltage in the wires tomorrow, but I'm pretty sure I know what I'll get. (I'll have to clamp the wires while a friend turns the key to on.)

Ideas on which relay to check? Which one is it?
Any other ideas?
July 14, 2008.

Hi tubergonz,

I don't think there is any relays involved. Check the fuses at underhood fuse box.

The grounding of the circuit is by the ECM.

Jul 15, 2008.
" Check the fuses at underhood fuse box. &Quot; Wouldn't I get more error codes? I understand several sensors get power thru the same fuse.

Running thru the possibilities, if a fuse replacement works great, but what if the fuse blows out again?
I've already checked the harness to the o2 sensor, but not the others for cuts, burns.

Jul 15, 2008.
Dang it. I checked all the fuses and none were blown.
I can only assume that there is an open circuit.
According to the Haynes manual for 98-99 accords, if the relay had failed then the engine mount control solenoid wouldn't have worked either.

I've run out of ideas.

Jul 15, 2008.
Hi tubergonz,

The syatem used on your car might have the HO2S getting its power from the main relay.

Check for power at the sensor coupler before looking for the fuses.

If you have a Yellow/Black wire, it should have battery voltage when ignition switch is turned on.

Next to it is the Orange wire and it goes to the ECM.

Measure the resistance of HO2S across the pins, you should get between 10 to 40 ohms. Hope you have wired the sensor correctly.

Jul 16, 2008.