P0118 erratic temp reading
Thread Starter
3rd Gear
Joined: Sep 2017
Posts: 3
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P0118 erratic temp reading
Looking for a little help! I've been reading for about three weeks on the issue.
2002 that I have had for about a month ETC issues. A little about the car 120k has long tube headers, Cold air intake and Corsa exhaust.
On two separate occasions a few weeks apart. The 1st time temp would go from 0-260 and could stop at any temp momentarily before moving. When at 0 car would sputter and buck. Lasted for about 5 miles car straitened out.
Several miles and no issues.
Three weeks or so later I start the car (sitting 2 days) instantly pegged out 260.
Here is the info I have related to the issue.
1. Code P0118
2. Resistance from ETC to PCM = 0
3. Ohm the sensor itself dipping in hot and cold water ohms raise in cold, lower in hot. I do not remember the specific ohms, but appeared to be functional.
4. Clear the P0118 on the DIC temp goes to normal (190) for a short period then back to 260.
5. Shut the car off 10-15 minutes. Start it up maxes out clear the P0118 again. Back to normal temp, drove around 20 minutes or so stayed right at normal temp.
Any and all help would be appreciated. I've read numerous post on corvette forums but have not really seen any conclusions. I have a video but do not know how to upload it.
2002 that I have had for about a month ETC issues. A little about the car 120k has long tube headers, Cold air intake and Corsa exhaust.
On two separate occasions a few weeks apart. The 1st time temp would go from 0-260 and could stop at any temp momentarily before moving. When at 0 car would sputter and buck. Lasted for about 5 miles car straitened out.
Several miles and no issues.
Three weeks or so later I start the car (sitting 2 days) instantly pegged out 260.
Here is the info I have related to the issue.
1. Code P0118
2. Resistance from ETC to PCM = 0
3. Ohm the sensor itself dipping in hot and cold water ohms raise in cold, lower in hot. I do not remember the specific ohms, but appeared to be functional.
4. Clear the P0118 on the DIC temp goes to normal (190) for a short period then back to 260.
5. Shut the car off 10-15 minutes. Start it up maxes out clear the P0118 again. Back to normal temp, drove around 20 minutes or so stayed right at normal temp.
Any and all help would be appreciated. I've read numerous post on corvette forums but have not really seen any conclusions. I have a video but do not know how to upload it.
Thread Starter
3rd Gear
Joined: Sep 2017
Posts: 3
Likes: 0
Thanks for the reply, I will definitely check that this evening.
What puzzles me is the overtemp then reset and a correct reading for about 30 seconds. I would think a shorted or grounded out wire would be constant with no movement of the car.
What puzzles me is the overtemp then reset and a correct reading for about 30 seconds. I would think a shorted or grounded out wire would be constant with no movement of the car.
Thread Starter
3rd Gear
Joined: Sep 2017
Posts: 3
Likes: 0
Ok another weird to me event today with the temp sensor.
Last night I was checking for ground and so forth and the car was showing over temp with the P0118 code. All the grounds I'm check are showing up good. So I go back in the house and read some more bits and pieces and some one said to check for constant 5v on one of the wires.
so I come home from work today unplug the sensor and turn key on and start checking the plug, yellow is showing constant 5v. Brown gets a momentary 0.01v pulse. Everything seems normal, I don't fully understand the pulse yet.
Plug the sensor back up and start the car after clearing the P0118 from where I unplugged it. Car runs for 15 minutes or so and rises to 180 no freaking out and hitting 260 like the night before.
Moral to the story the car has not moved 1" and now everything seems fine and operates like normal. I am not naive enough to believe the problem fixed itself, but can not understand what the trigger is.
any and all help at this point would be much appreciated.
Last night I was checking for ground and so forth and the car was showing over temp with the P0118 code. All the grounds I'm check are showing up good. So I go back in the house and read some more bits and pieces and some one said to check for constant 5v on one of the wires.
so I come home from work today unplug the sensor and turn key on and start checking the plug, yellow is showing constant 5v. Brown gets a momentary 0.01v pulse. Everything seems normal, I don't fully understand the pulse yet.
Plug the sensor back up and start the car after clearing the P0118 from where I unplugged it. Car runs for 15 minutes or so and rises to 180 no freaking out and hitting 260 like the night before.
Moral to the story the car has not moved 1" and now everything seems fine and operates like normal. I am not naive enough to believe the problem fixed itself, but can not understand what the trigger is.
any and all help at this point would be much appreciated.
Safety Car
Joined: Jun 2017
Posts: 4,786
Likes: 425
From: North Georgia, USA
That sounds like a sticky thermostat to me.
That's one of the few parts I just "throw" at a vehicle with symptoms. Symptoms for a sticky thermostat are inconsistent readings for engine temp on the gauges, or inconsistent ECT readings on the OBD-II live data stream. Wild swings in either direction can be caused by the thermostat sticking closed (hot coolant temps) or sticking open (low coolant temps).
You might also check some temperatures with a point-and-shoot infrared thermometer, to make sure the readings are valid and not just flakey sensors/wiring.
That's one of the few parts I just "throw" at a vehicle with symptoms. Symptoms for a sticky thermostat are inconsistent readings for engine temp on the gauges, or inconsistent ECT readings on the OBD-II live data stream. Wild swings in either direction can be caused by the thermostat sticking closed (hot coolant temps) or sticking open (low coolant temps).
You might also check some temperatures with a point-and-shoot infrared thermometer, to make sure the readings are valid and not just flakey sensors/wiring.
