3.0 2001 Ranger 4x4 XLT

I replaced the thermostat a couple weeks ago, along with radiator, water pump and hoses. Seemed to be fine for a week or so. Temperatures have gotten colder this week, and now the temp gauge doesn't budge. Check Engine Light came on. Free diagnosis told me the engine is running too cold.
My guess is that maybe the thermostat is stuck open, not allowing the engine to warm up to proper temperature. Does this seem like the probable cause?

If I replace the thermostat again, and it allows the engine to warm, then does the CEL go off on its own or does it need to be reset?

TIA,

Don

 

First thing I'd do is make sure you are full of coolant, You may just need a good burp.

Low coolant will give no heat to heater, and no coolant for temp sender to register.

 

you can reset the CEL by unhooking the battery negative for a minute or so and then reconnecting it.

 

Thank you to supercab and 420stackz. I cleared the engine code as you suggested and worked a few more bubbles out of the radiator. Ordered a spillproof funnel from Amazon but it wouldn't get here til tomorrow.

Thought I'd kept the old thermostat. Was prepared to put it back in but couldn't find it. Afraid to drive to parts store so in desperation took it to nearby franchise repair shop. The did a diagnosis and determined it was the sending unit, which gave me a sigh of relief, even though it didn't seem totally logical. Replaced that and still no heat. I told them to go ahead and replace the thermostat which solved the problem. They said the gasket sealer I used caused the thermostat to stay open. I don't know if that's the case or not, but at least the gauge works and the heater works. End result was $400 for a 6$ thermostat. I should have changed it myself but was exasperated by that time and not really sure what the problem was.

A good lesson in older vehicles. If you can't work on them yourself, you can hardly afford to hire the work done. $400 maintenance on a $25k vehicle is one thing. It feels a lot different on a $3k vehicle.

Anyway, thanks again for your assist. It is truly appreciated.

couch

 

Note: you DONT need to apply gasket maker. Order the OEM gasket for the thermostat. Snug up bolts on thermostat housing and call it a day. Ive done it this way for years on many makes and models and never lost a drop from the thermostat housing.

 

Thanks, I debated whether to add the sealant or not. Tried to error on the side of conservative and turned a small problem into a big one.

That's how I learn best.

me

 

That's how we all learn the best.