service engine soon (p0128) on 2004 BMW X5

service engine soon came up and i use my scantool to read and get p0128 and clear it and it cameup again a week after. Please what do i do?

by in Keller, VA on September 14, 2011
5 answers 2 comments
ANSWER by on September 14, 2011
P0128 Engine coolant temp sensor
ANSWER by on September 14, 2011
I would make sure your thermostat is working correctly before jumping to any conclusions. it is the most common failure for the 128 code. Roy
COMMENT by on September 14, 2011
mastertch6371 your correct i forgot to add that
ANSWER by on September 14, 2011
Change thermostat.
ANSWER by on September 14, 2011
this is obd2 trouble code table,http://www.chinasinoy.com/service/how-to-understand-trouble-codes-37.html it can help you understand the meaning of the code, for this code, you can try this, Verify coolant strength & level. Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary. Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary. Verify proper intake air temperature (IAT) sensor operation, replace if necessary. If the above items check out good, replace the thermostat.
ANSWER by on September 14, 2011
Yep! BMW, thermostat issue.
COMMENT by on September 15, 2011
yep, what a surprize. roy