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Our 2020 PHEV has been showing an emission or exhaust warning for about a year. The dealer can't ID the source. This car was charged outside for it's first 10 months and was severely damage by squirrels. They chewed up wiring harnesses both in front and back. Six weeks later, with shipping delays and other complications, we got the car back. I cleared a spot in the garage to charge it. The phantom error message appeared soon after the repair. Right now it is reading emissions system problem. It has also come up as an exhaust problem. The errors come up at all times, even with no ICE usage. Occasionally it disappears. But returns after a brief period. Has anyone else experienced any warnings like this? I have presumed it be related to the squirrel damage, but has it happened to others?
 

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2021 PHEV Touring HB, CA
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Our 2020 PHEV has been showing an emission or exhaust warning for about a year. The dealer can't ID the source. This car was charged outside for it's first 10 months and was severely damage by squirrels. They chewed up wiring harnesses both in front and back. Six weeks later, with shipping delays and other complications, we got the car back. I cleared a spot in the garage to charge it. The phantom error message appeared soon after the repair. Right now it is reading emissions system problem. It has also come up as an exhaust problem. The errors come up at all times, even with no ICE usage. Occasionally it disappears. But returns after a brief period. Has anyone else experienced any warnings like this? I have presumed it be related to the squirrel damage, but has it happened to others?
Oh, man. Rodent damage and intermittent errors are the worst.

Good luck, and please keep us posted. With no more of these being produced, the knowledge about these cars that is represented on this site could be priceless, as dealers "forget" more and more.
 

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I just got a low tire warning yesterday. I was out in the middle of nowhere. I checked the idewtire pressure using the tire inflation pump. All four tires were 36psi. I recalibrated the tpms. I had one tire replaced the day before (nail near the sidewall). Maybe they needed to calibrate the tpms and forgot.
When I bought the car I put the roadside warranty/rotate & balance service from my loIcal Discount Tire. The tire was $240, much more than the cost of the package.
 

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2018 PHEV Touring Atlanta, GA
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My tires all went low in cold weather. I topped them off. When the light stayed on I called the dealer. The system needs to be recalibrated each time to remove the warning.
It would seem that refilling the tires to the previous pressure should have cleared the warning, but if it didn't you can reset the TPMS yourself. On the infotainment screen go to Settings/Vehicle/TPMS Calibration.
 

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It would seem that refilling the tires to the previous pressure should have cleared the warning, but if it didn't you can reset the TPMS yourself. On the infotainment screen go to Settings/Vehicle/TPMS Calibration.
You have to recalibrate to get rid of the warning.
 

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Our 2020 PHEV has been showing an emission or exhaust warning for about a year. The dealer can't ID the source. This car was charged outside for it's first 10 months and was severely damage by squirrels. They chewed up wiring harnesses both in front and back. Six weeks later, with shipping delays and other complications, we got the car back. I cleared a spot in the garage to charge it. The phantom error message appeared soon after the repair. Right now it is reading emissions system problem. It has also come up as an exhaust problem. The errors come up at all times, even with no ICE usage. Occasionally it disappears. But returns after a brief period. Has anyone else experienced any warnings like this? I have presumed it be related to the squirrel damage, but has it happened to others?
Do you specific ODBII codes, in the order they appear?
 

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2018 PHEV Touring Atlanta, GA
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You have to recalibrate to get rid of the warning.
In some cars that can actually be an indication that there is something wrong with the TPMS system, if the light doesn't go out after you fill the tire(s) back to the same pressure they were at when you calibrated. Then again we don't have the usual TPMS that reads actual pressure, it is instead measuring wheel rotation and looking for a difference between wheels. In fact I'm surprised the light even comes on in winter, because if all four tires lose pressure evenly then there should be no difference in rotation speed between wheels.
 

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Our 2020 PHEV has been showing an emission or exhaust warning for about a year. The dealer can't ID the source. This car was charged outside for it's first 10 months and was severely damage by squirrels. They chewed up wiring harnesses both in front and back. Six weeks later, with shipping delays and other complications, we got the car back. I cleared a spot in the garage to charge it. The phantom error message appeared soon after the repair. Right now it is reading emissions system problem. It has also come up as an exhaust problem. The errors come up at all times, even with no ICE usage. Occasionally it disappears. But returns after a brief period. Has anyone else experienced any warnings like this? I have presumed it be related to the squirrel damage, but has it happened to others?
It sounds like a short to ground somewhere because you are getting ICE related warnings when ICE is off. . It will hard to find other than tracing the exhaust monitoring circuit. Try disconnect each section.of the harness one at a time at both ends and check for a short. That should narrow the location down.
 

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In some cars that can actually be an indication that there is something wrong with the TPMS system, if the light doesn't go out after you fill the tire(s) back to the same pressure they were at when you calibrated. Then again we don't have the usual TPMS that reads actual pressure, it is instead measuring wheel rotation and looking for a difference between wheels. In fact I'm surprised the light even comes on in winter, because if all four tires lose pressure evenly then there should be no difference in rotation speed between wheels.
I think the computer stores each tire's rotational speed when you calibrate. The light comes on anytime the rotational speed increases (smaller diameter => faster rotation) by a percentage of the original speed.
 

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2018 PHEV Touring Atlanta, GA
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I think the computer stores each tire's rotational speed when you calibrate. The light comes on anytime the rotational speed increases (smaller diameter => faster rotation) by a percentage of the original speed.
The system never knows how fast the car is actually going, it merely estimates mph by the wheel rotation speed multiplied by standard tire circumference. If the rotation speed of all four wheels changes, it has no idea if that's because the car has changed speed, or if it is because of a change in tire pressure. It assumes the former and adjusts the indicated mph on the instrument panel accordingly. Only if the speed of one wheel changes in relation to the others will it trigger the TPMS warning.

Wheels may have different rotation speeds due to differences in tire wear. I'm pretty sure what is being stored when calibrating TPMS is the differences in wheel rotation speed at the time of calibration, so that it can later detect if the rotation speed difference between wheels has changed. Of course it is relying on the owner to make sure that all four tires are at proper pressure when they calibrate.
 

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2020 Clarity Touring
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The system never knows how fast the car is actually going, it merely estimates mph by the wheel rotation speed multiplied by standard tire circumference. If the rotation speed of all four wheels changes, it has no idea if that's because the car has changed speed, or if it is because of a change in tire pressure. It assumes the former and adjusts the indicated mph on the instrument panel accordingly. Only if the speed of one wheel changes in relation to the others will it trigger the TPMS warning.

Wheels may have different rotation speeds due to differences in tire wear. I'm pretty sure what is being stored when calibrating TPMS is the differences in wheel rotation speed at the time of calibration, so that it can later detect if the rotation speed difference between wheels has changed. Of course it is relying on the owner to make sure that all four tires are at proper pressure when they calibrate.
And the TPMS must have some additional smarts as well since simply turning a corner or driving in a non-straight line will also cause wheels to turn at different rates relative to one another.
 
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