I have a 2004 PT Cruiser with the Turbo engine. It has about 51,000 miles on it and I’ve taken good care of it. (It’s only really had two problems: a power steering fluid leak, and the engine RPM sensor failing. Both were routine replacements.)
Recently when starting cold, the oil light stays on while starting and stays on as long as I drive the car. Turning the ignition off and back on will cause the oil light to turn off like normal. The car’s still 1000 miles from its next oil change. There are no codes in the ECU computer.
Does this light indicate an actual problem, or is it just a glitch? Should I go get my oil change early, or is it ok for another thousand miles of winter driving?
I’m definitely not a pro mechanic, and it’s been a long time since I went to mechanic’s school, and that was for motorcycles, not cars. That said, here’s what I think.
The oil light (assuming you’re talking about the actual oil light, and not the “check engine” light) is probably hooked up to the oil pressure sensor. It’s indicating low oil pressure. So there are two possibilities. Either you have low oil pressure, which is a bad thing, or the pressure sensor is malfunctioning.
If you’ve got low oil pressure, it could be a few things. Your oil pump could be bad. I doubt this – I think your oil pump is likely to be mechanically driven, and it would either work or not. And if it wasn’t working, your engine would have been destroyed pretty quickly.
You could have some sludging in your engine, blocking some oil passages. This isn’t good, but taking your car to your oil change place for an engine flush and new oil would probably fix it (assuming you trust your oil change place to actually do what you pay them to do, which is a whole issue in itself). Or you could have a clogged filter with a bad bypass valve.
the oil pressure switches on these are notorious for leaking and occasionally putting the light on. I have a 2004 SRT-4 (same engine as yours) and had to replace the oil pressure switch at about 80,000 miles.
check the oil level and have the oil pressure checked to be sure, though. an actual loss of oil pressure is a critical situation.
If it’s leaking, the concerns are getting oil on something that would be harmed by it (rubber parts like motor mounts, hoses, belts) and loss of oil to where it gets too low and the engine is damaged. The oil loss can range from minor seepage to a significant rapid drip under pressure, which might make it hard to maintain the level high enough. So it depends on how badly it’s leaking and what’s getting leaked on. However, oil pressure switch leakage and oil pressure switch malfunction are two different things; very seldom is one related to the other.
Your description suggests an electrical glitch rather than a mechanical failure, so my recommendation is to have the oil pressure switch replaced. If the light works normally with a new switch, you’re done. If the problem persists, the next thing to do is to have the oil pressure checked with a mechanical test gauge. If the oil pressure is within specs (under the conditions where the light stays on) and the light is still acting up, then some electrical troubleshooting is the next step.
AIUI on these particular switches, the leak is internal to the switch. oil gets past the diaphragm, and since the pressure on both sides of the diaphragm is now equal, the switch closes and lights the oil pressure warning. Again AIUI the PCM/cluster software will keep the warning light lit until at least the next key cycle, even if the problem corrects itself in the meantime.
I do not believe the PT has a “change oil light” so the light is a sensor that check oil pressure, not level - although low level can certainly cause low pressure.
A low oil pressure light is probably the single most critical “idiot” light you should worry about as it can certainly lead to an almost immediate failure of the engine that results in big dollars or a ruined engine. Do not take it lightly.
Possible causes (in order of severity):
Low oil level which could indicate burning or leaking
To ask a dumb question, why does it only happen on cold starts? It seems like it should either happen always or never.
Another quick question, the oil pressure sensor, do you need to empty the oil before pulling it? I assume not, since none of the directions I found online for replacing it mention that, but I’d like to be 100% crystal clear before I make a mess of my garage.
Those don’t really relate to the issue. While significantly low oil level can cause low pressure, proper oil level doesn’t necessarily mean the pressure is right, and engine temperature is not affected by oil pressure or lack thereof.