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Engine Code P0118 - HELP!

toddlnrd

toddlnrd

My first diesel!
Messages
208
Reaction score
11
Location
Garner, NC
Replaced the radiator and the water pump and finally have no leaks, but I have a P0118 engine code. I replaced the temp control sending unit, but still have the code.

What am I missing? When I was working in the truck, I had the batteries disconnected for a while. Does that have anything to do with the code?

The dash temp guage reads correct, but the Scanguage plugged into the ODB II port is reading 40 degrees F no matter what (did drop to 39 once). Engine idles at 800 rpms now at normal operating temp (per dash guage).

Any thoughts?

Thanks,
Todd
 
I know the code is:

P0118 ECT Sensor Circuit High Voltage

but that does not help me much.
 
Have you checked the coolant temp sensor yet? It is the 2 wire sensor in the t-stat housing.
 
I just spent hours myself chasing the same problem. Had a brand spankin new sensor, so checked everything else about three times. Turns out the sensor was *****t :incazzato:. Try a new one.
 
The one that i just replaced was only 3 months old. When I removed one of the battery leads, it did touch ground and arced a little bit. Would that have anything to do with it?

Could take it back and replace it again (third times is the charm).
 
gawd I hate that, spend hours and blood trying to trouble shoot, then find the problem, install new part which takes more hours and blood only to find out the new part is bad out of the box
 
toddlnrd said:
The one that i just replaced was only 3 months old. When I removed one of the battery leads, it did touch ground and arced a little bit. Would that have anything to do with it?

).
Click to expand...
No.
Drago said:
gawd I hate that, spend hours and blood trying to trouble shoot, then find the problem, install new part which takes more hours and blood only to find out the new part is bad out of the box
Click to expand...

It sucks.
 
Replaced the coolant temp sensor again at lunch today. Same thing, temp at ODBII a steady -40 degrees F.

I originally posted that the temp was reading 40, but it is really reading -40.
 
Do you have a shop manual? or maybe someone here does and can tell us the pin # on PCM plug for the PCM ground.
On OBDI its C8.

Sounds like you dont have a ground somewhere then. Did you test the new sensor to make sure its working?
 
Latest update.

I had to drop something off at home and tested the connector by doing the highly scientific "wiggle" test. While wiggling the connector, the engine rpms dropped to normal and the coolant temp rose to an expected 96 - 100 degrees (only ran for about 30 seconds). I chased down a connector at the local parts store and will splice it in tomorrow.

I will let you know my results. I am confident that this will fix my problem.

Thanks for everyone's input.

Todd
 
get your meter out and backprobe the sensor.

If I recall correctly, it should be feed a 5V ref signal.

When cold it should be somewhere around .5 v on the out side, around 4v when hot.

If you don't see 5v feed, check your wiring up to that point for breaks or chaffing.

If your values are wrong for hot and cold readings on the out side, suspect the sensor.

You can trace the wiring back to look for chaffing and/or breaks on the return wire.

If your scanner can read live data, look at the data stream for the sensor.

-40 is full cold, which would make me suspect a grounded wire (less than .5v return) if the sensor is tested good.

More for you to review: http://www.obd-codes.com/p0118

You can also meter the sensor for resistance to determine it's serviceability. I can't remember the values off the top of my head but resistance will go lower at the engine/sensor warms.
 
Sounds like your onto it.
Just to correct myself on OBDI the C8 pin is the temp sensor (not the ground)
 
great white said:
get your meter out and backprobe the sensor.

If I recall correctly, it should be feed a 5V ref signal.

When cold it should be somewhere around .5 v on the out side, around 4v when hot.

If you don't see 5v feed, check your wiring up to that point for breaks or chaffing.

If your values are wrong for hot and cold readings on the out side, suspect the sensor.

You can trace the wiring back to look for chaffing and/or breaks on the return wire.

If your scanner can read live data, look at the data stream for the sensor.

-40 is full cold, which would make me suspect a grounded wire (less than .5v return) if the sensor is tested good.

More for you to review: http://www.obd-codes.com/p0118

You can also meter the sensor for resistance to determine it's serviceability. I can't remember the values off the top of my head but resistance will go lower at the engine/sensor warms.
Click to expand...

Dang, looks like you were "wiggling" while I was typing.....:)
 
I replaced the connector at the coolant temp sensor and the problem is fixed.

Thanks to all for the suggestions and help.

In the last few days, I have installed a new radiator, water pump, lower rad hose, coolant temp sensor and connector!

Todd
 
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