Acura MDX P2237 Code: Oxygen Sensor Issue and SH-AWD Light Troubleshooting

P2237 refers to the oxygen sensor in bank 1, sensor 1. This code can be caused by either a failing sensor or wiring issues—though the sensor is more likely. A professional diagnosis would typically determine whether it's the sensor or its circuit. Regarding your catalytic converter replacement: if it was an OEM part, and your engine has been running well (no oil/coolant leaks, proper air-fuel ratios), it should last at least 100,000 miles. Replacement of the cat alone is unlikely to cause P2237. Could you share your vehicle's year and mileage? Also, how is the SH-AWD system performing?

Thanks for the clarification, cj1. The catalytic converter was replaced at the dealer’s recommendation due to emission warnings. I don’t remember the exact codes from that time, but after replacement, everything remained stable for about 6–8 months until now. I’m concerned because some sources suggest a failing cat could indicate more serious engine issues—like fuel system problems or internal combustion inefficiencies—but the dealer only said cats can wear out over time. The cost of replacement was high, and I don’t want to repeat it unless absolutely necessary.

Wiring faults in the oxygen sensor circuit are possible but less common than a failing sensor itself. A diagnostic scan will help determine whether the issue lies with the sensor or its wiring. If the catalytic converter was OEM and installed properly, it should last well beyond 100,000 miles under normal driving conditions—especially if there are no signs of oil burning or coolant leaks and air-fuel ratios are balanced. Could you confirm your vehicle’s year and current mileage? Also, how is the SH-AWD system behaving?

I’m planning to replace the oxygen sensor. I’ll monitor whether the P2237 code or the SH-AWD light clears after the replacement.

I’ve watched a video on replacing bank 1, sensor 1. DIY seems time-consuming and requires specialized tools. It might be a good opportunity to also replace spark plugs if they haven’t been done recently. Also, don’t forget the timing belt—especially since it was replaced at 106,000 miles. This is a critical maintenance item for vehicles with high mileage.

cj1, I already have the proper tools and have changed the spark plugs in the past. I’ll proceed with replacing the oxygen sensor first. I also had my timing belt and water pump replaced at 106,000 miles. Thanks for the helpful tips!

I just replaced the sensor this evening. It was easier than expected. However, the old sensor looked black—like oil had seeped into it. Is that normal? Does it suggest a fuel or oil leak issue?

No firsthand experience with this, but blackening of the sensor could indicate the engine is running too rich—possibly due to a clogged air filter, faulty fuel injector, or misfire. After replacing the sensor, check the long-term fuel trims in your OBD2 scan. This will help determine if there’s an underlying fuel system issue. Did the new sensor resolve both the P2237 code and the SH-AWD light?

So far, no check engine or SH-AWD lights have come back on. The vehicle is running smoothly.

Why not try using the Sonic Cruise feature and ask someone else to take photos of the sensor for a clearer view? That might help identify any visible signs of oil contamination or damage.

My check engine light comes on occasionally, but my airbag light and windshield wiper fluid light are also on. My wiper fluid is full—any idea what could be causing this?