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 note
Technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.
Reprinting, distribution, reproduction, exploitation in any form or disclosure of the contents of this document, even in part, is prohibited without our express, written approval and indication of the source. The schematic illustrations, pictures and descriptions serve only for the purposes of explanation and representation of the instructions and cannot be used as a basis for installation or assembly work. All rights reserved.
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