A common problem with the VW Polo 9N (2002-2010) is a constantly running cooling fan. This can drain the battery and indicate underlying issues. This article delves into using VCDS (Vag-Com Diagnostic System) to diagnose and potentially resolve this problem, specifically focusing on how to interpret the coding related to the air conditioning system. We will explore a real-world example of a 2007 Polo 9N with a persistent cooling fan issue.
Understanding the Problem: A Case Study
A 2007 VW Polo 9N presents with a cooling fan that runs continuously at low speed even when the engine is off, eventually depleting the battery. When the engine is running, the fan operates at high speed regardless of the engine temperature. Standard troubleshooting steps, such as replacing temperature sensors, have already been taken. The suspicion now falls on a faulty signal from the air conditioning module.
Using VCDS for Diagnosis: Engine Module Coding
To investigate the air conditioning module’s role, we can use VCDS to examine the engine module coding. In this specific case, the VCDS scan reveals the following information for the engine module (Address 01):
- Part No: 03E 906 023 B
- Component: SIMOS91 1.2l 4V 3015
- Coding: 0000071
The coding helper within VCDS provides a breakdown of this coding:
- 000?x: Can-Databus +1 = Anti-Lock Braking System (ABS) +2 = Airbags +4 = Climate Control (Climatronic)
- 000x?: Transmission 1 = 5-Speed Transmission
This indicates that the presence of climate control (Climatronic) is denoted by a “+4” in the coding. However, deciphering how to modify the existing coding (0000071) to disable the air conditioning requires a deeper understanding of the older style coding system. The challenge lies in translating this information into a practical solution for disabling the air conditioning via coding changes within the engine module.
Decoding the Coding Helper: VW Polo 9N Air Conditioning
The key lies in understanding how the binary system applies to the coding helper. Each digit represents a power of 2. The “+4” for Climate Control suggests that the 3rd bit (2^2 = 4) controls the air conditioning functionality.
However, without the full explanation of the coding structure for this specific engine control unit, definitively determining the correct modification to disable the air conditioning solely based on the provided information is challenging. Consulting a detailed VW Polo 9N specific coding guide or Ross-Tech’s VCDS support resources is recommended.
Conclusion: Further Steps
While the VCDS scan provides valuable insights into the Polo’s engine module and its coding, pinpointing the exact coding modification to disable the air conditioning requires further investigation. Referencing comprehensive resources specific to the VW Polo 9N and its SIMOS91 engine control unit is crucial. This case highlights the importance of understanding the nuances of VCDS coding and the need for model-specific information when troubleshooting complex automotive issues. Further diagnostics might be needed to definitively determine the root cause of the constantly running cooling fan. Remember to always proceed with caution when modifying vehicle coding and consult reliable resources to avoid unintended consequences.
