2013 Equinox P0037 Code

2013 Equinox LS, 4 cyl, 48k miles. Note, pistons, rings, and timing chain replaced at 42k.

After ~4 or 5 minutes of driving the CEL light came on and stayed on for the remainder of the drive. The OBD-II reader showed a P0037, HO2S Heater Control Circuit Low (Bank 1 Sensor 2) code. I believe it indicates a fault in the heating element of downstream O2 sensor. I cleared the code and it did not come back during the ride to work. The CEL did not affect driveability as far as I could tell.

Any suggestions on what to check? I’m not sure if this is covered under the Emissions 8/80k warranty, the book was a bit vague on the matter. If the light reappears, I will call the dealership.

Ed B.

The heater in the O2 sensor is there to warm the sensor during cold startup. It is the sensor downstream of the catalytic convertor and its job is to monitor convertor condition. If it fails, and they very often do, it doesn’t affect the engine’s operation although a slight bit more emissions may be created at cold startup. It could be controlled directly by the engines ECU but might be through a relay - giving more points of failure. Wiring issues and relay issues can cause a P0037 but the sensor is pretty likely the cause.

The P0037 seems like that should be covered under the emissions equipment warranty at 3 years and 48K.

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Just for our curiosity why were the pistons, rings and timing chain replaced at only 42K.



After GM upgraded the 2.4 Ecotec to Direct Injection the piston rings were wearing out 3 to 4 times faster than expected. Oil consumption started at 20k miles and steadily increased to 1qt/1500 miles at 42k. From what I’ve read my Equinox was a textbook case. Both the 2.4 and 3.6 6 cyl had problems with timing chain stretching after the DI consumption. The thread I started a ways back has more detail, it’s rather long.

Ed B.

hmmm … just curious, I wonder if the injector inside the cylinder is spraying a little gasoline directly onto the rings and diluting the lubricating oil, so they wear a little faster? I’ve heard of unexpected valve problems w/direct injection, I guess the gasoline in non-direct injection cools and cleans the valves as it flows by, but not a problem w/ ring and piston wear. Until today.

I can’t think how all that would affect the O2 sensor heating circuit, so probably a coincidence.


I’m pretty sure it’s a coincidence too. Anyway, the CEL came back on today on the way home. As far as I can tell the 02 sensor is only covered under the 3/36 warranty and it will be 4 years old in November. I’ll make an appt. with my independent mechanic next week.

Ed B.

This is an example of a two trip fault. The first failure is registered as a pending fault and the second trip failure in succession illuminates the check engine light.

The 8 year/80,000 emission warranty is for specific components; catalytic converter, PCM, check engine bulb and OBDII connector.

That sounds like it. Today the light stayed off running an errand. Came back on the return trip


Ed B.

Update, managed to get underneath and find the downstream O2 sensor. The wiring harness was not secured. It was rubbing against the CV axle and the insulation was worn through. I have a suspicion it was either knocked loose or not secured properly when the engine was reinstalled after the rebuild. Unfortunately the dealer changed hands on March 31st (the day I got it back) and it’s 6 months after the the repair. I’ll call the dealer, but I’m not optimistic.

I’m unable to put up on my ramps as the bumper and air dam won’t clear them. I’m a little concerned using a floor jack and jack stands on a unibody.

Ed B.

On the side where you need access, jack it up at the forward end of the “jacking zone” then put the jack stand as close as possible behind the jack along the same body weld line. Leave both jack and stand in place. At least, that’s what I do.

The manufacturers preferred safe jacking points are often shown in a diagram in the owner’s manual.

It’s good to be wary jacking at the wrong locations btw. For example one time a friend of mine asked me to help him rotate his tires. I explained he needed to find a diagram for the jacking locations firsts. He decided this info would be too hard for him to find, so he had a shop do the tire rotation job instead. See, being concerned about the jacking locations is a good thing … lol .

I had my local mechanic change the O2 sensor. Charged $109 for the part and $40 labor which I thought was very reasonable. The cost of the sensor at the local part stores was between a $100 and $120, online ~$65.

Ed B