Hi

Have a 2002 Sonata - V6 GLS - Love the car - has about 114k of mostly trouble free driving.
I'm hoping to get 200k out of it :-)

Lately though, I've been battling my check engine light. It complains about he same thing:
P0037 HO2s Bank 1 Sens 2 Heater circuit low.

I have replaced the oxygen sensor with one from Bosch. This was
a direct plug-in replacement. When I did that the check engine light went out on it's own.
I did not have to erase it. After a couple of weeks it has come back on. The code is the same.
I've also replaced a fuse in the box under the hood.

Any ideas of what to do next.

I've seen a few other posts on this forum where some other folks have had this problem.
What was done to finally resolve it?

Thanks

Dear pjm,

You may be suffering from connector corrosion. Since you said you paid the extra and bought the Bosch direct replacement, that should not be the problem. Get some spray electrical cleaner. disconnect the O2 connector, spray with cleaner, and work the connector in and out 5 times, spray again, blow or wipe off excess, and reconnect.

Byron

Hi Byron,

Thanks for the suggestion. I can only hope it is something that easy.
I gave it shot tonight. Sprayed some cleaner on the connector.
plugged and un-plugged a few times. cleared the code.
So far so good. We'll see if it stays off.

Thanks again

Did cleaning the connectors work?

It looked like it did for a little while, but then the light came back on (sigh).
Next I;m going to clear it. Then one at a time, I'm going to disconnect
the sensors till I get the same code. I'll try cleaning that one real good.

OK, after lots of trial and tribulation, I'm pretty sure I have finally solved this.
I ended up replacing both bank 1 oxygen sensors. The light has gone out on its own and so far
is staying out. I used the bosch direct replacement sensors. I really think I nailed it this time.
I have a much better sense of how the sensors work. The bank 1 sens 2 was tricky to find.
I'm glad that it its fixed. The car never seemed to run bad when the light was on, but I must
admit that it "feels" better now (might be all in my mind).

Just an update - Its been a couple of weeks now and the light is still out. Car is running fine.
In retrospect, I probably replaced the wrong sensor initially. Fortunately, I kept the old one
since it is probably still good. If anyone needs these sensors, advance autoparts has them
for right around $100. They are not that hard to replace. In particular the second one I did
has an access plate that covers it. Removing 2 screws makes it easily accessible.

Thanks to everyone for their suggestions.

Just in case anyone is still following this. The fix is solid. No more check engine light for months now.
Next up: change transmission fluid, then the dreaded timing belt!