Why does my oil light flicker on only when I idle?

My oil light flickers on when I idle, but only when I idle in drive. If I’m at an intersection and change to park, it goes away. I’m not sure if this has anything to do with it, but my engine shakes just a little(maybe loose motor mount), but it shakes less when I am in park. I also notice a foul smell coming from my heater, and I think it smells like burnt oil, but I’m not sure. I check my oil level and it is just fine. I got my last oil change a few weeks ago.

Have a look around the throat of the oil filler and the coolant filler openings - is there a scummy whitish residue there. This would indicate a blown cylinder head gasket with water vapour being forced into your oilways.

The original symptom appears to indicate low oil pressure, possibly caused by one or more of the following:

Clogged oil filter or pickup strainer (could be caused by the above if the filter was changed along with the oil)
Worn oil pump gears.
Worn bearings - main bearings and crankshaft journals in particular.
Or hopefully a defective oil pressure sensor.

Hang around for Rick to come along and shoot me down in flames and give you a more precise diagnosis but relying on experience, those are the points I would look into first.

If you are lucky it is just a bad sensing unit. Most are fairly cheap <20USD. Change it (or have it done) and see what happens

Well the first step would be to accurately check the oil level. Do this by either parking the car on level ground for several hours or by checking it with the engine fully warm, and shut off for at least 2 minutes. On many engines low oil level = low pressure. Also oil that has not been changed in a long time can have a lower pressure at idle.
The shaking would tend to indicate a low idle speed when in drive, which can also cause low oil pressure.
The burnt oil smell tends to indicate a leak, and a poor seal at the rear edge of the hood. (A rubber seal at the rear of the engine compartment that sticks up and pushes against the bottom of the hood when closed.) This seal, not only keeps the oil smell out, it also would keep any leaking Carbon Monoxide out of the inside of the car.
My advice
Check the oil, add or change as necessary.
Check and adjust the idle speed as necessary
Repair any leaks.
If that does not solve the problem then
Do a oil pressure test with a mechanical gauge
If bad, the problem is internal (and probably expensive) If OK
Verify that the wiring to the sender is intact and not grounding out anywhere.
If that is OK, replace the sender.

These three things make a low engine idle speed the most likely explanation. That’s the easiest and cheapest problem to solve, so I’d start there.

I still think adding 2 quarts of oil would be cheaper. :smiley:
(look up one post)

Look up to the OP. :slight_smile:

This is for the OP - I know Rick knows this, probably better than I do.

Oil pressure is roughly proportional to engine speed (at least until the pressure-relief valve opens) - this is due to the oil pump being positive displacement. But your low-oil-pressure idiot light is set to illuminate at a set pressure. So, when your idle speed falls too low, the idiot light goes on. (The same thing happens when your turn off your engine - the light comes on - except at that point you aren’t thinking about the problems of low oil pressure.) There’s little load on the engine at idle, so this may not be a problem, or it could be an early warning sign of problems to come. If the light goes out when you bump up the idle speed, things may be OK - or you could get this checked by measuring the pressure with an accurate mechanical gauge (or having a mechanic do this). Good luck.

Three hours sleep, that is my excuse and I am sticking to it.

What’s the make/model/year of your car? And roughly, how many miles do you have on your car? Checking the oil level is certainly the first step, but if that’s full, then you could have real problems. Your oil pump might be about to fail. In addition to the problems that’s been mentioned, you might have a crappy oil filter. which could be causing the problem. Having the oil light come on is not a good thing at all. Without proper lubrication, you’re adding wear and tear to the engine. Another problem is that for some reason, the idle on your car could be too low and having that adjusted could correct the problem.

When was the last time you had the oil changed on your car?

I have a 97 Sebring convertible with about 145000 miles. I don’t think it has anything to do with the oil filter because I got my oil changed not too long ago and these symptoms were happening both before and after I got it.


You forgot like at least “x” things:

The oh yeah, like, I’m sure
The bad connection in the dashboard
The short circuit in said above
The motivator
The car is Jonesing
The mechanic is on my nuts
The responder is drunk and/or stupid



In all seriousosity…

“Sender” = “Oxygen sensor”?
Cuz oxygen sensors really do suck. :mad:

Dude, WTF? :wink:
A little too much Christmas cheer?
Anyway in this case the sender in question is the oil pressure sender, often called an oil pressure switch.

I could ask you the same thing… (I’d prolly be out of line though)

Could not the “Sender” mean several different things"? Surely several things “send” shit to the computer? Including the O2 sensor?

P.s. Maybe.

Well since the tittle of the thread is Why does my oil light flicker on only when I idle? I thought it fairly safe to assume any reference to a sender in this thread would be about a sender concerning oil pressure. Also despite their rather confusing name, Oxygen sensors don’t sense oil pressure, they sense Oxygen.
::: scratches head:::
Guess I was wrong about it being obvious.

I’m sorry, of course, you’re obviously the expert on cars.

I was just making a joke…?..

If you’re a mechanic, and you don’t get it, then maybe you should search on O2 sensors and the BS surrounding them with regard to incompetent mechanics.

P.s. I searched… and found nothing…
Maybe it’s just local…
But anyway, EVERYTHING is the oxygen sensor… unless it is.

Excuse me while I go pass out.

Umm-that’s right-the oil light flickerator circuit is low on oxygen, so it needs to be readbusted to be in synch with the frequency of the piston return springs, otherwise it can result in carbon buildup of the muffler bearings.

A few weeks ago. Not me. The OP.