If the fault pattern listed above is reported, the cause may be a defective coolant temperature sensor. In addition, error codes (triggered by implausible sensor values) may be stored in the engine control unit.
Error code 'equivalent' to:
- P1556, 'Charge pressure control negative'.
In addition, with the potentially misleading turbocharger pressure error code (P1556), excessive engine knocking while idling could be indicative of a faulty sensor.
In this case, proceed as follows:
- Disconnect wire harness multi-plug from the engine control unit and the coolant temperature sensor and perform a continuity test.
- Check the contacts on both sides for corrosion and mechanical damage and repair them if necessary.
- Check the ground connections.
- Check that coolant temperature sensor is functioning properly. As guidelines, the specified resistance value should be _ 2080 Ω at 25°C and _ 289 Ω at 85°C respectively.
Replace the sensor if necessary (see Figure 1.).
Hella coolant temperature sensor: 6PT009309-331
Then clear the entries present in the error memory.
Figure 1.
Important safety notice
The following technical information and tips for practical use have been set up by HELLA in order to offer professional support to automotive workshops in their daily work. The information available here on this website is only to be used by appropriately trained specialist staff.
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