Check engine light
Thread Starter
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Elder User
Joined: May 2001
Posts: 692
Likes: 1
From: Coon Rapids, MN
Check engine light
My check engine light comes on once the truck has reached its operating temp. But the catch is it only happens when im driving around town and not on the highway. I just recently installed a 180 degree thermo to replace my defective 195 and the engine light started comming on a few days after I replaced it. The codes I pulled from the ECM are: KOEO=11 system ok, 41 (Oxygen sensor signal fault, switching not detected) that was in the continuous memory
KOER= 41 System running lean, 52 Power steering pressure switch open
A couple things I could think of would be a bad oxygen sensor or fuel pressure regulator. Anyone have a plan of attack before I spend money on something I dont need? Thanks
KOER= 41 System running lean, 52 Power steering pressure switch open
A couple things I could think of would be a bad oxygen sensor or fuel pressure regulator. Anyone have a plan of attack before I spend money on something I dont need? Thanks
Posting Guru
Joined: Dec 2001
Posts: 2,017
Likes: 2
From: Southeast FLA
Check engine light
I could be wrong, but I thought I read the lowest you could go with our computerized trucks was a 190 degree thermostat.
If you only changed it to cool the engine better during hard use, I'd suggest using a 50/50 mix of water to antifreeze (the lower the anti-freeze, the better it cools - but then you do need some in there to lubricate the water pump seals), and add a bottle of Redline Water Wetter instead (meaning you probably need put the right thermostat back in and reach your end-goal by a different means).
Maybe an aftermarket 'performance chip' could lower the expected temp. range of the computer... but they aren't supposed to do much for I-6's otherwise, so it probably isn't worht the money.
If you only changed it to cool the engine better during hard use, I'd suggest using a 50/50 mix of water to antifreeze (the lower the anti-freeze, the better it cools - but then you do need some in there to lubricate the water pump seals), and add a bottle of Redline Water Wetter instead (meaning you probably need put the right thermostat back in and reach your end-goal by a different means).
Maybe an aftermarket 'performance chip' could lower the expected temp. range of the computer... but they aren't supposed to do much for I-6's otherwise, so it probably isn't worht the money.
Elder User
Joined: Jul 2001
Posts: 937
Likes: 0
Check engine light
If you're getting a code for the HEGO, I'd replace that first - unless you've recently done it. They're essentially maintenance items anyway and should be replaced on a regualar basis. You can get Bosch brand sensors at Autozone for around $41.
Then disconnect the batt for 10 minutes or so, drive it again and see what codes still appear.
Then disconnect the batt for 10 minutes or so, drive it again and see what codes still appear.
Thread Starter
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Elder User
Joined: May 2001
Posts: 692
Likes: 1
From: Coon Rapids, MN
Check engine light
Thanks guys, I replaced the 195 with a 180 just because I heard it was good to. Now my temp reads between the N and the cool mark. MOre towards the n. I replace the O2 and see what happens.
Senior User
Joined: Jan 2002
Posts: 185
Likes: 0
From: Central Florida, USA
Check engine light
You probably should go back to the 190° thermostat. At 180° the engine coolent may not get hot enough to get the fuel flow down to run from rich start. Particularly if you live north of I-10. I tried that once for about 1 week. Every time the outside air temperature was below about 70°f and the thermostat opened the coolent temperature would drop below the run sensor temperature and the computer would change back to a richer mixture for the injectors. The engine would run rough and the mpg would get lower. Turns out that the engine will run fine at 195° and as long as the coolent is maintained and the system is working. I have run my truck for hours with the coolent temperature at about 230° and all is still well at 160,000 miles.
