'99 Navigator issues


El Presidente
Staff member
Paid Member
While I was working out of town last week, apparently the kids borrowed the Navigator and had some problems. :(

They were on their way back from town when the Navigator "quit running" and the "oil warning lamp" came on. Terrified they had messed up Dad's Navigator, they had AAA tow it back to the house without even trying to restart it. :eek:

I checked everything out and found it about 1-1/2 quarts low on oil. It has been burning oil as of late but it hasn't been that long since I last checked it. Anyways, I topped off the oil and it started right up with no difficulty and no unusual noises. The CEL was illuminated. I checked the codes and there were several. The codes returned pointed to lean conditions on both banks, TPS and O2 sensor codes. It also seemed to be idling a little high at around 1000 rpms but otherwise seemed good. I cleared the codes and ran it a bit to see if the CEL would return. It did and again it showed both banks lean. :confused:

I ordered a new TPS, and picked up an IAC valve. I plan to clean the MAF, swap the TPS and IACV and check for vacuum leaks. I think the oil light may have just been from the engine quitting unexpectedly?

I'm not sure where else to investigate except possibly throw new O2 sensors at it. It sits much more than being driven and it has been pretty reliable since I've owned it. Any further ideas appreciated.