97 Accord with OBD1 H22. P13 ecu.

I have a persistent CEL code 41 for primary o2 sensor. I had it before the swap. Changed o2 sensor with Denso sensor. Didn't fix the problem. Ended up swapping in an OBD1 H22. new motor and new ecu gives the same CEL. O2 sensor measures 15ohms across the black wires, well within the 10-40ohm spec. Harness wires to heater circuit show 12v with ignition on. So, 2 different ecus, new o2 sensor, all volt and resistance readings within spec. Yet that pesky code 41 persists. Anyone have any ideas what else I can check? The car runs fine, just tired of looking at the CEL.

 

seafoam and look for an exhaust leak anywhere from the exhaust manifold to any point past the oxygen sensor

you will see white smoke billowing out from the exhaust somewhere if there is a leak

common leak is at the exhaust flange gasket as people tighten too much at one bolt without alternating causing a leak

 

Do you think an exhaust leak would affect the o2 heater? I'll give the seafoam a try. It can't hurt. BTW this happened with the stock exhaust manifold on the f22 and now aftermarket header on the h22. I torqued them in sequence, but we'll try and see how it goes.

 

exhaust leaks kill oxygen sensors

just test and rule out an exhaust leak and we can go from there