I have had the P0128 code (Coolant Temp Below Thermostat Regulating Temperature) in my mini r53 2006.

Friends, in December I changed the thermostat and expansion tank and just today I turned on the Service Engine Check Light. What do you advise me?
Sorry for my English

Thanks

 

OK if it is the SERVICE ENGINE and not the EML, then there is an emissions issue. The p0128 could be a low coolant level.

 

When you replaced your thermostat, did you replace it with the stock 91°C (195°F) version, or the optional cooler 82°C (180°F) version that some use when racing? If the 'cooler' version, the P0128 code can result; the fix would be to replace with the stock thermostat.

How does your coolant level look? It should be at the half-way mark of the tank with engine off and cold (check with light placed on top of tank; see below). If it's low, the P0128 code can result.

If the above checks out, look to see if the coolant temp sensor is still connected.

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Thanks for you advice r53coop and AoxoMoxoA.

AoxoMoxoA, I don't know what thermostat install in my mini, the thermostat is aftermarket. Checking with the scanner the fan turns on at 109 ºC, but when I turn on the AC, the fan turns on every moment and the temperature is between 87ºC and 90ºC.

The coolant level is like your photo and the temperature sensor is OK and connected. Other question is: What temperature should the fan turn on? and the stock thermostat (91ºC) means the fan turn on when the temperature up to 92ºC.

Again thank you and apologies for my bad English

 

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Check Thermostat:

Thermostat is wide open at 196°F (91°C).

​When cold engine first comes up to 195°F (90°C), you should see the temperature cycle down from 195°F (90°C), to 189°F (87°C) as the thermostat opens, then it will go back up again until the temp rises beyond.

If it's not cycling, you have a faulty thermostat.

Check Fan:

Let engine idle while you watch the temp rise.

At 221°F (105°C), Lo-Speed fan comes on, then turns off at 214°F (101°C).

At 234°F (112°C), Hi-Speed fan comes on, then reverts to Lo-Speed @ 227°F (108°C).

If temp gets to 238°F (114°C) and still no fan, turn engine off.

* It should be noted that if the A/C is on, the fan will cycle on and off regardless of coolant temperature

 

Hello my friend AoxoMoxoA

I tell you to change the thermostat for a calorstat brand thermostat, change the coolant fluid and purge the radiator, the car already makes the cycles that you mentioned in the previous answer.

Thank you for your great support, my friend. God bless you. Peace.