2009 S80 "Engine Temperature High"

StevenStowik · Post by **StevenStowik** » 23 Feb 2019, 11:46

Hello Folks, hope all is well.

I have an issue with my '09 S80 that I have been trying to resolve since 2017. My car, especially on hot summer days, has an issue with overheating. Whenever I am stopped or parked for an extended period of time, especially with the air conditioning on with the temperature set low, my car begins to print "Engine Temperature High Reduce Speed." Once I begin driving, the text disappears and everything seems normal. This problem can also be resolved if I turn the heat on... seems logical. Coolant levels seem good, both fans on the radiator turn on, as they need to, or so it seems. Just recently I replaced the coolant temperature sensor/thermostat, in an attempt to alleviate the issue, and found out that the part was broken. Unfortunately, with a brand new sensor, this issue is still ongoing.

Just recently my check engine light turned on... I purchased an OBD-II tester to find out what the code is. The code that it brings up is P0128 -- Coolant Thermostat Malfunction. This is a brand new part that I replaced myself, so I know it was done properly. So now my question here is, what could be wrong? This issue... could this have caused another broken thermostat? If so, what could have caused that, to happen twice now? Could this code be appearing due to another issue, if so, what could that other issue be?

Thank you in advance for sharing your knowledge and time with me.

dj_v70 · Post by **dj_v70** » 23 Feb 2019, 16:13

Did you get the thermostat code before replacing the thermostat? If not, you probably have a problem with your new sensor/thermostat.

Your high temp problem is likely the radiator is clogged. Either internally or externally. That diagnosis assumes that you are sure that the fan is working properly.

The problem is not thermostat. If it was, you would have had high temp while driving also.

StevenStowik · Post by **StevenStowik** » 24 Feb 2019, 21:27

The thermostat was replaced about 3 months ago. This code only started showing up about a week or so ago. I cleared the code about 3 days ago and it hasn’t shown up yet. But the overheating issue does still persist.

Now assuming that the issue is the radiator is clogged, how would I go about removing the clog? Also, would it only be clogged in the radiator or could it possibly be somewhere else in the coolant circuit?

Post by **RickHaleParker** » 24 Feb 2019, 23:57

P0128 means the engine is not warming up at the expected rate. Did you go cheap or aftermarket on the thermostat?

Post by **abscate** » 25 Feb 2019, 07:55

THermostat should have cost about $125 for part. Less is probably a bad part.

StevenStowik · Post by **StevenStowik** » 25 Feb 2019, 10:44

Spot on... thermostat cost me about $120.

dj_v70 · Post by **dj_v70** » 25 Feb 2019, 15:40

StevenStowik wrote: ↑24 Feb 2019, 21:27 Now assuming that the issue is the radiator is clogged, how would I go about removing the clog? Also, would it only be clogged in the radiator or could it possibly be somewhere else in the coolant circuit?

Look externally at radiator. Can you see leaves or other debris stuck in fins. If not, 90% probability that it is clogged internally. This is the narrowest part of circuit, so generally is the only area that gets clogged. The fact that high temperature goes away while car is rolling is because more air is forced through the radiator fins while driving.

Double check:
a) that fins don’t have debris stuck in them. If so, use garden hose to clear.
b) your radiator fans are working. Put car in drive with AC on and wait for high temp. Make sure fan is on. If not, you have a fan or fan thermal switch issue.
c) remove the radiator and either get it flow tested or just replace it. Generally, I don’t replace any parts without testing them but in this case I would just replace it if the price was right.

Most internally clogs are due to improper maintenance of radiator coolant. Either someone was adding tap water to circuit (takes a couple of years) or coolant wasn’t ever replaced on schedule.

StevenStowik · Post by **StevenStowik** » 25 Feb 2019, 21:06

Thank you for all of that info. My radiator isn’t clogged at all, I checked it by shining a light through it and it is very well clean. On top of that, I take my car to a touchless car wash weekly in the winter for the salt on the road, and the robotic arm blasts water right into the radiator fins. That should be clean as a whistle. As far as an internal clog, I would like to take it to get flow tested. As of right now that seems like it would be the best course of action.

As far as tap water being in the system, there wouldn’t be a trace of any tap water. I never use tap water, whenever I change my coolant I use the 50/50 pre-diluted fluid.

But as far as an internal clog, that seems logical. And it also seems like it could possibly be a reason the car isn’t getting up to temperature in time causing that P0128 code.

Post by **RickHaleParker** » 26 Feb 2019, 02:56

You might want to get a scanner that can read fault codes for the outside temperature sensors.
Incorrect data will cause incorrect calculations, see the section in Red below.
You may not have a problem in the cooling system. The problem maybe in the outside temperature readings.
A Volvo DiCE clone and VIDA 2014D_Repack is a good investment.

Is your outside temperature gauge working correctly?

-----------------------------------------------------------------------

P0128 = ECM-201A Thermostat. Faulty signal

Diagnostic trouble code (DTC) information ECM-201A

Condition
During the engine warm up phase the way the engine temperature should increase is calculated. Factors such as engine load and the start temperature are taken into account. This test takes place during the engine warm-up phase (under “normal operation”) and continues until the engine temperature has reached 84 °C. For the test to start, the starting temperature of the engine must be below 35 °C, the outside temperature must be between -7 and +35 °C and at least 15 minutes must have passed since the engine was last run.
The diagnostic trouble code (DTC) is stored if the calculated increase in temperature does not correspond to the actual increase (measured by the engine coolant temperature (ECT) sensor).

Hint:
This diagnostic trouble code (DTC) can also be caused by faults that store diagnostic trouble codes (DTCs) for outside temperature sensors.

Substitute value
None.

Possible source
Damaged engine coolant temperature (ECT) sensor
Damaged thermostat.

Fault symptoms
Malfunction indicator lamp (MIL) lit.

dj_v70 · Post by **dj_v70** » 27 Feb 2019, 01:19

RickHaleParker,
Everything you wrote makes sense to me. However, based on OP inputs, it appears to me that P0128 and hot engine at idle are likely 2 different issues. It is not clear to me (and hence possibly to OP) whether you postulate both symptoms are same issue or not. Could you please clarify.