I have a 2019 Buick Enclave Essence with the V6. It is throwing a code P257D, My check engine light was on but went off and its still throwing the code. All I can find online is something about the engine hood switch related to the ECM. Has anyone else had this problem? I realize it maybe just as simple as replacing the hood switch but I just wanted to see if anyone else had this problem and it ended up being the ECM needed to be replaced.

How many miles? That'* related to cam timing being off. Chain maybe?

For my answer I will assume the hood is closed completely.

Looks like an implausible signal has been received from the hood switch. I've never seen this issue. I don't think this would require an ECM replacement. Has someone told you this?

My guess is that the hood switch is out of adjustment or failed.

Has this vehicle ever had any front end damage?

I don't know what code I looked at. I've never seen a code for a hood latch.Not sure why they use it. What does it do?

I found this with a video that sort of explains it. My question is WHY?

https://www.engine-codes.com/p257d.html

I said the same thing.

Why do I need a sensor to tell me that my hood is open?

If I'm sitting in the driver'* seat and I don't notice that the hood is open, I'm certainly not going to notice the words "HOOD OPEN" in 1/4"-tall letters next to the odometer.

My feeling is that hood sensors came along either as an additional security sensor and/or as a safety sensor for remote start. I rented a few Chrysler products years ago that did not know the hood state but had remote start. They blip the horn twice before cranking when remote start is commanded. I haven't seen any others that do this with remote start, and all of those have a hood sensor.

The reason I mention that security might have caused it is the Ford D3 cars (Five Hundred, Montego, and Freestyle). They were notorious for the car alarm going off randomly as they got older, and a couple that I had worked on I traced it to defective hood sensors. Bypass them and no more random alarms. This was a pain to diagnose on the first one. I finally figured it out by keeping a friend'* Five Hundred for a few days and parking it in the garage locked and alarmed. It never did it. More frustrating. Parked it outside the next morning and the sun got on it for probably an hour and it did it. One thing led to another and I tried bypassing the hood sensor. Voila' no more problem. A few years later I read that a few others out there had figured this out as well. I don't believe the early D3s offered remote start as an option, but the later ones did, so maybe they were just preparing for that? Maybe someone else with inside information has that answer.

Anyways back on subject: If the hood sensor is causing this error, I'd replace the hood sensor. If the ECM went bad, of all symptoms that a bad ECM could cause, it would choose something besides a hood state error. That'* a BCM function anyways.

Engineers having fun.

Yeah and beancounters avoiding lawsuits with the remote start.

Personally, hood sensor or not, I commandeer all keys for a car whether it has remote start or push button start or key start before I reach very far into anything under the hood. I'm not trusting my appendages to any lowest-bid nameless hood sensor manufacturer.