Regulating throttle failure
Information on diagnostics
Will the malfunction indicator lamp not go out? Why is the engine temperature increasing? Why is the “Exhaust gas repair shop” display lit? This may be caused by a broken regulating throttle. You can find out about the functions of the regulating throttle and possible solutions for these problems here.
Possible complaints:
- Indication of “Emission, Workshop” on the multifunction display
- Engine temperature increases
- Error light is on constantly
- “Shutdown shuddering” after shutting down the engine
These complaints may be due to a defective or damaged regulating throttle.
FUNCTIONS OF THE REGULATING THROTTLE¹
The pressure difference alone between the exhaust and the intake side will be inadequate for the high exhaust gas return rates required in connection with Diesel vehicles. In order to increase the vacuum, “control bodies” are fitted in the intake manifold for precisely controlling the exhaust gas return rates. When shutting down the engine, the regulating throttle is closed early so as to avoid any “shutdown shuddering”.
¹ In practice a number of different terms are used for regulating throttles, like throttle valve, Diesel valve, or intake-manifold throttle.
The regulating throttle and the engine fan are protected by the same fuse. When this fuse blows, the engine fan will also stop running – the engine temperature can increase.
Possible manufacturer-specific error codes can be, for example:
- Fault code P2102 “Throttle Actuator Control Motor Circuit”
- Fault code 19557 “Motor for Intake Manifold Flap”
- Fault code 17075 “Engine coolant blower motor”
REMEDY
- With the aid of an engine tester perform an actuator diagnosis. Through the actuator diagnosis the regulating throttle is driven in intervals. If switching can be felt and
- heard, then the power supply will be okay.
- A defective regulating throttle must be replaced by a new one.
- Check the fuse. Replace a blown fuse by a new fuse of the same amp. rating.
Never insert a fuse with a higher fuse rating compared to the rating (10 amps) specified by the manufacturer.
We do not recommend cleaning of the regulating throttle:
- In the case of a defective regulating throttle suffering from the damage described overleaf, cleaning will not result in an improvement.
- A functional regulating throttle could be damaged by cleaning it.
