Fusion low temperature issues

[DoctorJay]

The "Check engine" light has been on on my 2006 Fusion for well over a year. The code indicates the engine is running too cool, but to my knowledge this is actually good for the car so I haven't replaced the thermostat. I use full synthetic oil which does not sludge (and to my knowledge running cool does not cause sludging even with cheap oil). Is there a way to permanently turn off the engine light for this code? I've reset it a couple of times but it comes on again in 3 or 4 weeks.

[fusionff]

There is no way to ignore one error code, I think your best bet is to replace the thermostat. Who knows when the CEL is also for something else.

[xmech2k]

That's not good for your engine. It won't damage anything, I think, but it was designed to run at a certain temperature. For instance, the computer makes the engine run a rich fuel mixture until the coolant reaches a certain temp.

[rfruth]

It could damage something, the cat may be cleaning up the mess (that caused the CEL in the first place) ask your dealer how much a catalytic converter is (and be sitting down when you ask)

[akirby]

If it was good for the car why do they use a thermostat in the first place? GET IT FIXED!

[drolds1]

You've fallen into the common trap of assuming that the OBDII code tells you exactly what's wrong. What if you replaced the thermostat and the light stayed on? What would you assume then? Would you replace the coolant temp sensor, the cylinder head temp sensor?

 

Who told you it's good for the car? That philosophy is left over from the old days when cars regularly overheated. If it's truly running too cool, then the ECU is going to compensate for a constantly cold engine by richening the air/fuel ratio and you are wasting fuel. Gas prices being what they are, can you really ignore that? As rfruth says, you may be getting more unburnt fuel into your cats, as well as mucking up your 02 sensors. That could lead to a very expensive repair bill

 

I assume you don't live in a county in TN that has emissions inspections. If so, a CEL being on is an automatic failure. Even if it was off at the time, you still might not pass.

 

As akirby asks, why do you think your engine was designed to operate at a certain temperature?

 

Just for the record, this is a common problem with 2006 Fusions, especially the 2.3L.

[Dyoct]

You've fallen into the common trap of assuming that the OBDII code tells you exactly what's wrong. What if you replaced the thermostat and the light stayed on? What would you assume then? Would you replace the coolant temp sensor, the cylinder head temp sensor?

 

Who told you it's good for the car? That philosophy is left over from the old days when cars regularly overheated. If it's truly running too cool, then the ECU is going to compensate for a constantly cold engine by richening the air/fuel ratio and you are wasting fuel. Gas prices being what they are, can you really ignore that? As rfruth says, you may be getting more unburnt fuel into your cats, as well as mucking up your 02 sensors. That could lead to a very expensive repair bill

 

I assume you don't live in a county in TN that has emissions inspections. If so, a CEL being on is an automatic failure. Even if it was off at the time, you still might not pass.

 

As akirby asks, why do you think your engine was designed to operate at a certain temperature?

 

Just for the record, this is a common problem with 2006 Fusions, especially the 2.3L.

 

It's a common problem because it's programmed into the OBD system now. Thermostats are wear items but nobody replaces them. My Volvo was exhibiting symptoms of slow to warm up, never getting warmed up in the winter, ran rich and the exhaust would never clear up in the cold and cabin heat was weak. Two winters ago I went to change the thermostat and I'm assuming the original one was in there because it just fell apart out of the housing once removed. New t-stat and full tune up and the car ran much better; gas mileage went up and the exhaust cleared up. I found that funny because it passed "emissions" testing no problems here.

 

A former customer's 96 Ranger kept failing emissions because it would not clear the P1000 code despite running hundreds of miles before "testing." Turned out his thermostat stuck open and not allowing the vehicle to get up to temp.

 

Wife complained of low heat in her Mustang last year. Changed the thermostat, had the original in it. She always gripes of low gas mileage however last month I drove it for our holiday break and it got better mileage than my Fusion does currently.