febi outlines some issues with thermostats on BMW, MINI, Peugeot, Citroën and DS models. This relates to febi part numbers 103197 and 170321.
Problem
- The engine is unable to reach operating temperature and a lack of heating in the passenger compartment.
- Illumination of the coolant temperature warning lamp; engine coolant discharging from the expansion bottle; engine cooling fan operating at maximum speed. Engine warning lamp illuminated – related to the symptoms listed above. These possible fault codes may be stored in the engine ECU: P0115 Coolant temperature sensor malfunction.
P0116 Coolant temperature outside specified range.P0597 Electric thermostat heater implausible.
P0598 Electric thermostat signal low.
P0599 Electric thermostat signal high.
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The presence of coolant under the vehicle and a reduced level of coolant in the expansion bottle.
Cause
The vehicles listed above can suffer from a number of issues relating to the engine cooling system, thermostat, or the housing. These include the following:
The thermostat incorporated in the coolant outlet housing becomes stuck in the ‘open’ position, resulting in the engine failing to reach operating temperature.
The thermostat incorporated in the coolant outlet housing becomes stuck in the ‘closed’ position, causing the engine to overheat.
The original polyamide material used ages under the influence of constant engine heating, cooling cycles and vibration. The thermostat housing can distort or crack, leading to coolant leaks.
Solution
Due to the issues and symptoms listed above, the vehicle manufacturer has modified the design of the thermostat housing. The updated design benefits from an electronically controlled thermostat, a reinforced structure, and a new configuration of the sensors – which may require an additional 2 x 2-way connector, subject to original vehicle equipment.
Therefore, diagnose and identify any fault codes which cause the warning lamps to illuminate. Replace the faulty coolant thermostat housing, fill the cooling system with fresh coolant, and bleed the air from the system.
Note: When replacing the thermostat housing, check all other coolant pipes for their condition and replace as necessary.
