Hi
new to the forum. i have a 2002 accord with 118k miles that recently after a car wash and oil change, the oil pressure light came on a stays on blinking. i took it to my mechanic and he put a manual pressure gauge on and found that the oil pressure was normal. he changed the oil pressure sensor but the light still is blinking. he believes that having the car washed, under body wash, might have shorted out the harness. been driving the car for a week and it seems fine, no noticeable difference in performance or sounds coming from the engine. thoughts?
Yes. My thought is that you have to have it fixed. If the pressure was verified manually and the sensor replaced, then the assumption of a wiring problem is reasonable. So now someone has to find it and fix it.
I agree with @cigroller
Pay the mechanic to diagnose and repair the wiring problem
If you ignore this, you won’t know when there actually is an oil pressure problem, because you’ve “trained” yourself to ignore the blinking light
I agree that it should be fixed.
However, if the blinking is consistant, as if it’s intentional, first check your owner’s manual. It may have some hidden meaning, such as “time to change your oil”.
If it’s blinking randomly, it’s likely either wiring or a weak connection. To find it, I’d suggest stopping by the dealer’s parts department and asking the guy there to print a copy of the schematic for the light as well as the wiring diagram. That’ll give you the data to troubleshoot the problem as well as telling you if there’s a relay in the circuit.
I am not familiar with the layout of the engine but my first thought after reading the OP was that the wire to the oil pressure warning switch might be pinched by the oil filter.
That it’s a 12 year old Accord makes it a prime candidate for electrical problems. I agree, look for a bad, rusted or worn wiring or connection. It may come on intermittently, but regular blinking is an electrical problem or a message. @same gives a good take on it.
Right from the manual:
This indicator should light when the ignition switch is ON (II), and go out after the engine starts. It should never come on when the engine is running. If it starts flashing, it indicates that the oil pressure dropped very low for a moment, then recovered. If the indicator stays on with the engine running, it shows that the engine has lost oil pressure and serious engine damage is possible. In either case, you should take immediate action.
It seems it is sending a message. Is the engine idling low are erratically?
The engine is idling fine.
@PvtPublic, the oil pressure was verified good with a gauge at a shop. It’s a wiring problem.
Though it’s true that mountainbike’s suggestion about other meanings the light might have was a good one. It just seems that the light means the usual thing.
If this was my 12 year old car, I would not pay for someone to fix this. He knows the pressure is ok, it was checked buy a mechanical gauge. I would just put a piece of tape over the light and check the oil level regularly. Of course, where I live a 12 year old car is getting very near the end of its useful life.
oldtimer . . .
What if the engine develops a real oil pressure problem?
I have no idea where OP lives. I live in southern california, and a 12 year old car is not even close to rusted out, and may have several useful years ahead of it
Some questions that might be food for thought if this turns out to not be a wiring issue.
What were the oil pressure readings?
Reading taken on a hot or cold engine?
What type of motor oil is in the engine?
What about the possibility that the reading is actually too low and it’s considered good because of a faulty spec in a service manual?
The reason I bring up the latter is because one of my manuals states that 6 PSI of oil pressure at 1800 RPM on a GM 3.8 engine is fine. Nothing could be further from the truth and who knows where the publishers came up with that 6 number.
Six PSI will barely open the circuit, if at all, on the oil pressure sending unit.
@ok4450 - maybe it was a typo and was supposed to say 16 ! (?) That is odd.
“6psi of oil pressure at 1800 RPM . . . is fine.”
Huh?!
I suspect whoever wrote that was high on crack at the time . . .
That same guy probably also wrote that sky high cholesterol and being 100lbs overweight was okay
I need to lose weight, and my cholesterol is too high, but I have sense enough to know it’s not okay
That manual plainly states 6 PSI of oil pressure. That manual also has other incorrect specs.
One involves compression readings and it states that 105 PSI is acceptable on an engine with other cylinders at 150.
Another manual I have states that a 37% cylinder differential is acceptable and also states that .024 of an inch oil clearance on crank bearings is fine. Think the latter wouldn’t turn an oil light on in a heartbeat? Methinks someone missed a zero… 
“after a car wash and oil change, the oil pressure light came on a stays on blinking”
While I don’t disagree with anyone, the first thing I’d do is get that oil changed again somewhere else using a factory OEM filter. To me it is possible the filter is not to spec and is intermittantly causing the oil pressure issue. Putting a guage on it is ok but not the same as having a full time guage that tells you what the pressure is at higher speed or higher temp. I agree get it fixed one way or the other so you know.
Do any of you guys know if this warning light is on a relay?
I was thinking that perhaps the carwash forced water into the underhood relay box.
The schematic shows a yellow/red wire going to the oil pressure switch. Before it meets the switch there is a splice with the yellow/red going to a chassis multiplex box located in the underhood fuse block.
Maybe the issue is that water entered the multiplex box and the ground is in the box instead of the oil pressure sending unit as the box
The oil pressure switch could be unplugged and the engine run like that for test purposes. If the oil light still flickers then it has to be a waterlogged multiplex box at fault; all assuming the oil pressure tests as normal with the manual gauge.
Thank you, my trusted friend, for following up on my query. I miss my access to a database repair system.
A dumb idea but I would add half a quart and see if it affects the light ???
BTW, the car does not have to be rusted but salt air can do a number on wiring over time. CA has it’s share of coast line.