My daughter has a 2005 Hyundai Elantra with 85K miles. We bought the car with just one owner who sold it at 60K. The car needed a lot of work, and the hits just keep coming. This time, the engine light came on, and the code indicated the oil was overheating. The mechanic says this code has a 50% false positive track record. I wager this is a false alarm because the car was driven only 8 miles in city conditions when the light came on. (Yet, the day before it went a good distance without an issue.) The oil is clean and full.
In case there is an issue brewing here, is there a way to diagnose this or catch warning signs before damage to the engine occurs? Should she keep driving but check the oil more frequently checking for thick and/or gummy oil (indicating thermal breakdown)…or is that too late?
The car does not have a temperature gauge on the oil. What would it cost to install one, and is it worth installing? Is this labor intensive? Other thoughts? Thanks!
[Admins: I am seeking factual answers, but if you feel this is more of an opinion question, feel free to move this post with my apologies.]
What is ‘the engine light’, a ‘check engine light’ that comes on, usually yellow is OK to drive on, if it flashes however it could damage the emissions system if you continue to drive much. Since you had the code read it seems to be a check engine light.
If the light is red however that is usually a stop ASAP condition.
I would venture a guess that it is not the engine oil temperature but the transmission oil temperature. And city driving could cause that while highway driving is just fine. As such you need to check the condition of the transmission fluid, which may be not easy to do on some cars.
Did a quick look at it and it does seem to be engine oil temperature which is needed for correct variable valve timing, thus emissions related, which explains why it’s a check engine code instead of a pull over light.
One thing to check is the oil viscosity (or more likely just change it with the proper viscosity). I’m not sure how it works on a Hyundia but the Nissan variable valve timing is very sensitive to oil viscosity, and yes tends to throw an equivalent trouble nuisance code.
The other thing you could do is have a IR thermometer on hand to read the head temperature. But I would not go any further until it happens a second time (and change the oil)
I would think anyone with the capability to add an after market oil temp gauge (and sensor) will also have the ability to replace the sensor in theirs first, and with a muiltimeter, probably check it to see if it’s working. Some very, very quick checking on google suggests that a oil temp sensor on the Elantra is cheap and easily accessible.
If it were my car, I’d first test it to see if it’s working (I’m assuming resistance changes with temp, could be wrong), if the resistance values aren’t as expected, drop a new one in.
However, if they are as expected, then it could be a wiring or ECU issue which is a whole other thing.
And I know you (OP) said she only drove 8 miles, but don’t discount the possibility that the oil is actually overheating, so that’s something to be checked as well. Don’t forget, it could be a symptom of bigger issue.
I would check the temp sensor and possibly just replace it if it’s as cheap and easy as stated upthread. Also switch to fully synthetic oil if you haven’t already, as it will offer more protection from heat. Finally, there are oil system cleaning products and procedures a mechanic can use to flush out your oil system. It could be that something is preventing your oil from circulating fully, which could cause this issue.
These two are where my head is on this one. It starts with knowing what the temp should be when the error code is thrown, then verifying that the oil is, indeed, above that threshold temp.
If it is, then you have one kind of problem. If it isn’t, then you have a sensor or sensor wiring problem, or even – possibly – a problem in the circuit that is erroneously throwing that code despite normal oil temp and a properly functioning sensor (far less likely, but … possible).
The engine oil temp is highly dependent on the coolant temps. Because of your variable valve timing they may have installed an oil temp gauge with a setting a little too close to engine temps. If the coolant temps are running on the high side of normal it may not trigger an over heat warning but may trigger a high oil temp warning.
Something like that happened to my wife’s car. Hot oil light came on after a few miles of driving. We’d let it cool, start it up again, get a few more miles and the light would come on again.
The problem was a thermostat that was stuck. Apparently at start up the engine coolant doesn’t flow through the radiator so the engine quickly gets up to ideal operating temperature. Then the thermostat trips and starts letting coolant through the radiator so it can do its job.
In my wife’s car, that thermostat was stuck closed, so the engine wouldn’t leave “heat up quickly” mode, so the angry light (rightfully) came on.
So that’s another “small” thing that might cause the observed behaviour.
I agree. IANAMechanic, but it seems to me the oil stays cool because the engine coolant works. (I assume most normal cars do not have a separate oil cooler) If the oil is getting hot, why isn’t the coolant also overheating? Or is it?
I used to have the opposite problem - in my 91 Civic and in many cars of that era, the thermostat would fail open, coolant would always go through the radiator and the car would never heat up - not fun in the winter.
