Oxygen sensor code: Is this the wiring or the ECU?

Hello. I recently had my Hyundai Entourage (2008) come up with the following engine codes: P0057 and P0037, both related to the downstream oxygen sensors. The generic description of the code is heated oxygen sensor heater control circuit low. As I understand this code, it is signaling that there is too much current passing through the heater circuit. The oxygen sensors test out OK for resistance, around 10 Ohms each and disconnecting them entirely and rerunning the test after driving a few times yields the same code. So I suspect the issue is not with the sensors but either the wiring or the ECU. I’d be a little surprised at a sudden short in the wires for both sensors but I suppose stranger things have happened. Oh and the fuse for the oxygen sensors has not blown. I am correct in reading these codes to mean there is an apparent short? Or are there any other things that could cause this to happen?

Those faults can be caused by a short to ground, an open circuit or an open in the power circuit. Check the fuse, there are two fuses for the oxygen sensor heaters; one for the upstream O2 heaters and one for the downstream O2 heaters.

Thanks, as I mentioned in the post, the fuses are OK. I’ll check on the cables to see if there is a sign they are shorted.

Here’s what I would do . . . make sure the downstream oxygen sensor heater circuit power and ground are good when you turn on the ignition

If it is, I’m inclined to believe the sensors themselves are the problem

oxygen sensor heater circuit fault codes are very common, and the heaters in the sensors tend to fail, after several years of work

I am having the same problem. Has there been any solution to this problem?

2007 Hyundai Entourage 2017

Have you checked the two fuses @Larry_Damron ?