Hi folks,
just had happy 6 months with my disco w/o any troubles, yay! But now my P1118 codes are back. The truck had this issue before, see pretext here: Service Engine Soon Warning? - Land Rover Forums - Land Rover Enthusiast Forum

Recently I had the water pump replaced, as its belt was not looking good, i.e. the belt looked frayed part didn't seem in good shape - there seemed to be a bad bearing inside.

When the pump was replaced known issues came back: my P1118 codes are logged, check engine comes on, and the truck is loosing coolant - not much but before I didn't refill coolant for months- I check every few weeks, when I check my oil level.

My UltraGauge reports that the engine temperature is fine, i.e. 200-210F. This is also reported from the dashboard, with a steady temp gauge at 3 o'clock. Also gas consumption seems normal with 14,8 highway MPG.

I wonder what happened and what the best way to fix it would be. Replace sensors - I just replaced both radiator sensors a few months back. Also thinking about doing the job myself.

Thanks for advice.

j.

 

1. Check fluids every week, pick a day, like Saturday morning, etc. Borrow a coolant presure tester and test at 16 PSI for 30 minutes, the leak will show up.

2. 1118 is the temp sensor at the bottom (about 3 inches up) on right side of radiator. It tells computer when outlet water is above 284F. It drops resistance as temp increases. That means that a skinned wire or any short to ground will also make this code. It could be a short that comes and goes. You'll need to inspect cable for as much of the path as possoble. The RAVE has exact resistance measure and the color code of the wire to follow.

3. Would unplug sensor, and also check wiring.

 

Thanks Savannah - much appreciated, as always!

 

I checked the coolant for exhaust and unfortunately it came back positive. Wondering wether the ode is related to head gasket issue. However the truck drives fine, but with a head gasket issue that bad - meaning bad enough to heat up the coolant to trigger the sensor I would expect some performance loss.

I don't really want to do anything about the head gasket unless I have to.

Are my assumptions valid, i.e.
- can a leaking head gasket trigger the code P1118?
- can I draw any conclusion from the fact that my UltraGauge scanner reports consistently fine temperatures 200-210F, while gas consumption and performance are normal, i.e. the head gasket issue is not that bad?
- Do I risk any other damages by not fixing the head gasket as long as the truck drives fine?

Will come back with the results of the pressure test.

 

Only temperature (activation of sensor) or a grounded wire (insulation rub, etc.) would bring on that signal. I'm with you, if that kind of heat, seem like there would be other HG tattle-tale issues (not to be confused with Tattletales on Piedmont Road for those in Atlanta). If Ultra Gauge says it is not over heating, I would be tempted to really examine the cable for that lower rad sensor. Not sure if you could substitute a sensor (not inside the rad, just taped to cable) for testing, the logic is to compare engine temp vs exit temp for a stuck thermostat. So the exact value varies.

As for a tiny HG leak, they usually don't stay tiny forever.

 

Finally solved my Check Engline light issue related to Code P1118 logged.

In fact there were wires that had rubbed off their insulation near the place were the engine oil goes in. I guess dripping oil over bad old insulation may have made things worse.

The fix was so ridiculously easy that it is ironic I was going to sell the truck for cheap due to a check engine I couldn't fix. My mechanic who worked on the power steering actually found it.

There was also a camshaft sensor P0340 that probably had the same root cause, since both sensors run off the same harness.

The leaking coolant has also been fixed, by applying HG magic fixing fluid.

Back to happy trucking. Cheers Savannah - you were right all along by pointing towards the wiring

 

Hope you have 200,000 more; but just in case start putting quarters in a fruit jar to save up for head gaskets in the future. Might also consider one of those 180F soft spring stats to lower temps just a bit.