My grandson is driving a 2008 Impala with a 3.5 flex fuel engine that has been “in the family” for a number of year. It has 143K and probably 90K of those miles have been since I owned it and then passed it on to him. He got a “you’re out of luck” message that the oil pressure was low and advised shut down immreiately. So, he, pulled over, checked the oil (last changed 2,600 miles ago and regularly changed the whole time we have had it). Oil level was OK. After waiting a few minutes, he decided to start it up again. No light, no knocking, ran fine the rest of the way home. Oil sending unit / wiring, oil pump, worn bearings - we recognize the problem is potentially critical but then, no light and no further warnings. I don’t know how to check the sending unit - or where it is for that matter. We need to figure out if this is a fluke or the real deal. Suggestions appreciated please
Remove the sending unit. Install a mechanical gauge. Confirm proper oil pressure. If it doesn’t have good pressure, you have a problem… where? Could be worn bearings, a bad pump, broken releief valve clogged, cracked or leaking oil pickup.
If the oil pressure is good, check the wiring and connector, clean them and install a new sending unit.
I agree with Mustangman, if mechanical gauge shows good, most likely a bad oil pressure switch/sender, always check for damaged wiring… I have replaced a lot of them over the years, they are pretty cheap and easy to replace (most of the time lol), and if yours has 143K miles on it, good chance it is bad…
Just to add to other possibilities, could be some sludge or trash that is blocking the oil pick up tube screen and when turning the engine off, it drops back down in the pan until it gets sucked back up again later… Could always run some engine flush through it and change the oil and watch for anything other than thin oil coming out of the oil pan… at next oil change…
If it were me I’d just replace the sending unit for $30 or so. Maybe just do an oil and filter change at the same time. I had that with my riviera one morning and immediately went to the dealer. They said just replace the sending unit which I did and still happy a couple hundred thousand later. Of course better to put a gauge on to make sure. A lot of times they’ll leak and dump the oil in no time so replacement is kinda preventative anyway.
I like the idea of the gauge - but I don’t own one. So, this was my throw a part at it and hope it solves the problem plan. I appreciate all the good advice.
Thanks! Good suggestions
Thank you. Step by step instructions are great as ae the possible problems. I’d thought of some of those but there are several I’d several on your list I hadn’t considered.
If the code is read, it might tell you some good news like " faulty signal from oil pressure sensor." That would be nice to hear. That won’t be what it will say since immediate shutdown was suggested, but you can hope.
I was lucky but the van was two years old. The sensor may be around $40 and in the old days we would just change it and hope for the best which usually happened.
make sure you all understand that the oil pressure light is different than the oil level light. If the warning comes back on, you can have no oil pressure and it still have all the oil in it.
Good point. I understand that difference and have tried to explain it to the grandson. I think he gets it.