Oh boy, hoping this isn't as big of a problem as it seems like it might be.

2006 RL, 143k miles

Got it the car this morning, and the battery was dead - no idea why, haven't had any electrical issues since replacing my alternator a little over a year ago. Jumped the car, and after a few seconds of hard cranking, it started right up. But the oil pressure light was on. So I shut the car off and checked the dipstick - it was indeed low, which was also a surprise after a year and a half of almost no oil consumption between changes. So I topped it off (took maybe 3/4 quart to get it back to the full line), restarted the car, and went to work.

When I left work, the engine was difficult to start, and the oil pressure light was steadily blinking. I shut off the car, and checked the oil, which was still at the same level as when I topped it off. Hopped back in the car, it started right up, and the oil pressure light was off.

Is this possibly just the oil pressure sensor? Oil pump? Big engine destroying problems? The combination of sudden starting issues and intermittent oil pressure lights seems very concerning. Car drove totally fine once it got started, no weird sounds.

 

I'd replace the oil pressure switch to start given that it is easy to do and inexpensive. You might as well replace the vtec solenoid gasket while you're down there. I replaced mine recently. See below where the switch is. You will need thread sealant should you decide to replace it.

 

Now that I think about it some more, I have a feeling it is your battery, given that your battery was dead.

 

Thanks! After messing with it a bit more, I think it is either battery or alternator (I put in an aftermarket alternator due to cashflow last year, against the advice of literally everyone). Turned it on again and ALL of the ABS, AFS, TC, Airbag, etc lights came on. Would low batter voltage cause just the oil pressure light to blink sometimes? Seems to only happen after it has a hard time starting. Runs fine once it's on with no weird sounds, seems unlikely that the oil pressure switch and battery/alternator would start having problems at the exact same time.

 

UPDATE:

Swapped a new battery in, good as new. Tested the battery with a multimeter and the cold voltage was way down at around 10.4, dropped to like 8.7 during start. Apparently a bad battery CAN throw an oil pressure light with no other symptoms than suddenly hard starts.

 

It's probably that the voltage drops so low from the dying battery, that there isn't enough voltage for all the electrical systems to actually work properly - who knows what sort of random system failures you'll see from this scenario !