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2007 Mercedes-Benz C280 P0128 Fault: Coolant Temperature at 177°F and Possible Thermostat Issues

Model: 2007 Mercedes Benz C280 Fault Code: P0128 Posted: 2015-05-20 17:43

Hello, I'm experiencing intermittent P0128 fault on my wife's 2007 Mercedes-Benz C280. The OBD2 scanner shows the coolant temperature as 177°F (83°C) when the warning light activates—this occurred while we were outside in the driveway. Is 177°F considered high for a cooling system? What is the expected normal range for coolant temperature under typical driving conditions? The car is used primarily during summer, but this year has been unusually cold, with temperatures dropping to 5°C overnight. I'm wondering if the low ambient temperature could be contributing to the issue or if there's another underlying cause. Any insights into what might trigger P0128 and how to diagnose it would be greatly appreciated.

Related fault codes
P0128
Comments (2)
Anonymous 2015-05-21 08:48

A coolant temperature of 177°F (83°C) is actually on the lower side, not high—this suggests the thermostat may be malfunctioning or incorrectly rated. It's a good time to perform a full coolant system service: inspect for leaks, check hoses, replace the thermostat if necessary, and flush and refill the cooling system with the correct coolant type and specification.

Anonymous 2015-11-04 13:56

In many cases of P0128 on Mercedes-Benz C280 models, the issue stems from a stuck thermostat. The most reliable fix is replacing the thermostat with one that matches the vehicle's specifications. This often resolves the fault code and prevents recurring engine warnings.