Help...Check Engine Light

[MNSteve]

For future reference: If you ever get a check engine light, and don't have an OBD scanner, take your vehicle to any AutoZone, O'Reilly's, or pretty much any auto parts store. They will read the error code for free.

Doesn't the OBD system have a memory of recent events? Can one see what happened even when the check-engine light has reset?

My experience with these OBD error codes is that they're pretty cryptic. Knowing the code and the one-line "explanation" might not help much without someone to interpret it.

 

[Thevenin]

Doesn't the OBD system have a memory of recent events? Can one see what happened even when the check-engine light has reset?

My experience with these OBD error codes is that they're pretty cryptic. Knowing the code and the one-line "explanation" might not help much without someone to interpret it.

The ECU records the most recent Diagnostic Trouble Code (DTC) on most vehicles. Sometimes when a DTC trips, it will take a flash of all active PIDs (temperature, RPM, etc). If you request trouble codes through OBD2, the ECU should report appropriately. But that is as far as my knowledge goes.
https://en.wikipedia.org/wiki/OBD-II_PIDs#Service_02

DTCs can be pretty cryptic, but they're a terrific starting point for for you to narrow down potential causes. In my old Pontiac, I had a P0420 (vapor pressure alarm) code that haunted me whenever I filled up the tank. AutoZone tried to sell me several hundred dollars' worth of O₂ sensors, and the mechanic would've tried to replace my catalytic converter. But armed with the error code and Google, I figured out that my habit of "topping off" the tank was forcing fuel into the vapor recovery system, tripping the pressure sensor. I stopped topping off the tank, and stopped getting the light.

 

[el kepis]

The exact thing happened to my 2019 Touring with 800 miles on it. Exact thing. A search of this site pointed me in the right direction and calmed my worries.
After several "re-starts" all the system error messages went away except the CEL, which stayed on. Car was driveable.
A trip to the dealer 24 hours later, he read the codes and reset. Said it was a know thing, some low-voltage reading during charging can trip the codes.
All good now, 5 days later. But weird when it happened.

 

[Lowell_Greenberg]

The ECU records the most recent Diagnostic Trouble Code (DTC) on most vehicles. Sometimes when a DTC trips, it will take a flash of all active PIDs (temperature, RPM, etc). If you request trouble codes through OBD2, the ECU should report appropriately. But that is as far as my knowledge goes.
https://en.wikipedia.org/wiki/OBD-II_PIDs#Service_02

DTCs can be pretty cryptic, but they're a terrific starting point for for you to narrow down potential causes. In my old Pontiac, I had a P0420 (vapor pressure alarm) code that haunted me whenever I filled up the tank. AutoZone tried to sell me several hundred dollars' worth of O₂ sensors, and the mechanic would've tried to replace my catalytic converter. But armed with the error code and Google, I figured out that my habit of "topping off" the tank was forcing fuel into the vapor recovery system, tripping the pressure sensor. I stopped topping off the tank, and stopped getting the light.

Well they found multiple DTC codes: p1d00, u0200. U1204. U1600, u160c. They cleared all of them, found they did not reset and checked connections at battery control module. They charged the battery at 220v several times and found no issues. The conclusion was that if the situation reoccurs- they will troubleshoot further.

They mentioned a blog/bulletin board that suggested the above should resolve it. But unless I am missing something, I am unclear how anything they did is not equivalent to being unable to find cause and hoping it never comes back. Am I right?

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[craze1cars]

You are right. They have no idea what happened and are hoping it doesn’t happen again.

 

[Lowell_Greenberg]

You are right. They have no idea what happened and are hoping it doesn’t happen again.

Well- the service advisor did call me back. He said they basically plugged in the car and the clearing of codes AND software updates took place automatically. However they did not spell out what updates took place. I can't believe coming back for the same issue will serve mine or their interest. So I will keep my fingers crossed- and talk to the car daily about being predictable and well behaved

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[MNSteve]

So I will keep my fingers crossed- and talk to the car daily about being predictable and well behaved.

The good news is that a few folks here have reported that they had issues very early in the life of their car that went away and never happened again. My uneducated guess is an issue with the 12 volt battery, which could indeed clear up on its own.