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Discussion Starter · #1 ·
A few weeks ago, my check engine light came on. I went out an bought an Actron OBDII scanner to see what error codes I was getting. It read the following:

2 Codes
P0128
MIL ON
MONITORS
0 Inc
7 READY
MISFIRE
FUEL
COMP
CATALYST
EVAP
02 SENSOR
02 Htr

I tried searching for that code on this forum but nothing related came up. According to the book that my Actron came with, P0128 means "Coolant Temp Below Thermostat Regulating Temp". Not sure what that means. I would greatly appreciate anyone's input on this. Are these simple fixes or does it require a trip to the dealer?

Thanks in advance.
Eugene
 

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2006-2009 Range Rover Sport
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This is from the RRS S/C workshop manual (same engine):


DTC:
P012800

Description:
Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)

Possible causes:
* Contaminated coolant
* Engine coolant thermostat failure
* ECT sensor failure - Note: ECT sensor DTC may also be flagged

Action:
Check the coolant level/condition and thermostat operation. Check for ECT sensor DTCs.
 

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Discussion Starter · #3 ·
Thanks for the response. Do you know why my Actron is stating that there are "2 codes" when it only gives me one (P0128)? Also, the code refers to engine coolant, etc. but the Actron states that I have a misfire somewhere and mentions the 02 sensor and heater. Am I reading all of this correctly? Thanks in advance.
 

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Discussion Starter · #6 ·
RR Family said:
I had the same code on mine - but for cylinder #7. I had to change the ignition coil and it was gone.

Any other symptoms? Mine was noticeably missing.
RR Family - How can you tell which cylinder had the issue? When I used my scanner, it didn't read which cylinder had the issue. The car seems to run strong and haven't noticed anything wrong besides the check engine light. The OBD II code P0128 refers to "Coolant Temp Below Thermostat Regulating Temperature". Not sure how that code is related to "misfires". Also, when you say that the ignition coil was "noticebly missing", what do you mean by that?

03rangiemark said:
You can use an OBD II scanner on a 2007 RR? :think:
03rangiemark - I used an Actron CP9125 scanner (OBD II) bought from Autozone for $60.
 

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I'm sorry - brain phart. I was thinking OBD-I. :oops: Mine is an OBD-II/CANbus too.
Luckily, I haven't had to look for a while (I'm jinxing myself), but I think some of the codes include which cylinder.
 

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Discussion Starter · #8 ·
Replaced the thermostat today and erased the OBD II code. The original thermostat seal was warped. So far so good. Thanks to everyone for their input. So far, no code.
 

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Hi All!

Recently I had an error code P0128, which is "Coolant Temp below Thermostat Regulating Temp." Scanner told me to replace the Thermostat. Vehicle has 157,000 miles, I have had it for 3 years, and I purchased at 105,000 miles. Not had any Coolant system 'issues' that were abnormal, apart from having to replace the Radiator and a couple of hoses. All of this was done at least 20,000 miles ago, with no follow-up issues afterwards. I put a new Thermostat in about a week ago, and 2 days later the orange error message "Service Engine Soon" went away automatically. 2 days later it came on again. Lost some Coolant changing the Thermostat, but replaced with exactly the same type. What's going on? Is this a really, really, really, silly question - i.e. do I need to simply have the fault code 'cleared' by a machine / hand-held scanner? (I don't have one, never owned one, and don't know much about them). Car is running very smoothly by the way. Heating and Cooling are working correctly. There are no coolant leaks that I can see or smell, and I have not needed to top up the Coolant. There are 4 hex-head bolts on the Thermostat that need to be removed to take off the Thermostat - 3 of them are quite easy, but the back, lower (if you are standing in front of the engine bay looking forward into the engine) bolt is difficult to get to - I was not able to get a Torque Wrench in there, but I'm confident that it's tight enough.

From earlier comments in this thread, maybe I've got other issues going on, but I figured I would ask for your comments and feedback before I start investigating further.

By the way, if you live in cold weather, and you haven't checked / replaced your ENTIRE PCV (crankcase ventilation) system, DO IT NOW! Covered to death on this forum, for very good reason. I had this on my to-do list last winter, as a preventative maintenance project, ordered the parts, and one day I noticed some oil dripping from beneath the back of the engine, before I had time to fit the new parts. Limped home carefully, and felt extremely pleased with myself for already having all parts onhand. My leak came from the small tricky hose that connects to the bottom of the Separator - Perished and split, and clearly never been changed (had original hose clamp on it). Sorry to mix different subjects in one thread.....

Thanks, Simon.
 
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