NA - Toyota troubleshooting

[Lindberg]

The check engine light on my 2007 Toyota Matrix often comes on when it's cold or wet out, and stays on until we have a few warm days.

I pulled the codes below. One related to the cat or o2 sensors, and the other I can't figure out. I find several explanations online for this code, but none really make sense.

Does anyone know what this other code means? And what could cause these codes to appear only in cold weather?

 

[Sierra_Hotel]

Yaw rate sensor, apparently:

https://www.autocodes.com/c0371_toyota.html

No explanation on the weather impacting it except maybe just a bad connection or ground.

 

[Lindberg]

Yaw rate sensor, apparently:

https://www.autocodes.com/c0371_toyota.html

No explanation on the weather impacting it except maybe just a bad connection or ground.

Thanks. I have seen that, but I've also seen this code identified as relating to the MAF sensor. I'll see if I can find the location of the Yaw sensor and check it's connections. Any idea what would make the exhaust code come on only in the cold?

 

[AV8R_87]

Cold catalytic converters are less efficient, and will generate a fault code during the catalyst efficiency check.
The way that works is the engine will run lean for a while, then switch to a rich condition (monitored using the pre-cat O2 sensor), and will time how long it takes for the post-cat O2 sensor to switch from lean to rich. Too short of a time, the cat is deemed bad.
One way to help things is to use a tired pre-cat O2 sensor (the switch slower and generate a fault code) and install it in the post-cat position. It will make the ECU think the cat is better.

 

[Sierra_Hotel]

Thanks. I have seen that, but I've also seen this code identified as relating to the MAF sensor. I'll see if I can find the location of the Yaw sensor and check it's connections. Any idea what would make the exhaust code come on only in the cold?

Pretty sure a MAF sensor would be a P code, almost certain those are the powertrain ones, and C codes are chassis ones.

 

[asicer]

Yaw rate sensor, apparently:

2007 Matrix is a bit early for stability control, isn't it?

 

[Lindberg]

Cold catalytic converters are less efficient, and will generate a fault code during the catalyst efficiency check.
The way that works is the engine will run lean for a while, then switch to a rich condition (monitored using the pre-cat O2 sensor), and will time how long it takes for the post-cat O2 sensor to switch from lean to rich. Too short of a time, the cat is deemed bad.
One way to help things is to use a tired pre-cat O2 sensor (the switch slower and generate a fault code) and install it in the post-cat position. It will make the ECU think the cat is better.

I would I find such a sensor?

 

[AV8R_87]

By the time the cats get weak, the front O2 sensors get a bit tired as well and start throwing codes. I usually keep the old ones after I replace them.

 

[Lindberg]

By the time the cats get weak, the front O2 sensors get a bit tired as well and start throwing codes. I usually keep the old ones after I replace them.

Ok, so replace the front sensor and move the old one to the back?

 

[Sierra_Hotel]

2007 Matrix is a bit early for stability control, isn't it?

I see listings for it going back to 2004. I would have thought so, too, though.

 

[AV8R_87]

Ok, so replace the front sensor and move the old one to the back?

Yes. Not guaranteed to work, but worth a try.