This article addresses the common issue of fault code 17695 (Boost Pressure Control Valve (N249) Open Circuit) in the Audi TT 1.8T, specifically focusing on the 17695 VCDS code for vehicles with VIN TRUWX28N511041808, using VCDS version 21.3.0.0. We’ll explore potential causes and troubleshooting steps to help you resolve this problem.
Understanding the 17695 VCDS Code in Your Audi TT
The 17695 fault code, often accompanied by P1287, indicates an open circuit in the N249 boost pressure control valve. This valve plays a crucial role in regulating boost pressure in your 1.8T engine, and a malfunction can lead to performance issues, limp mode, and hard starting. The VCDS scan provided reveals this issue alongside other faults, potentially related to a recent engine repair.
Possible Causes of the N249 Open Circuit
Several factors can contribute to the 17695 code:
- Faulty N249 Valve: The valve itself may be defective due to internal damage or wear.
- Wiring Issues: Damaged wiring, loose connections, or corroded terminals in the N249 circuit can cause an open circuit. Given the described electrical gremlins and engine bay work, this is a prime suspect.
- Vacuum Leaks: While the code indicates an electrical fault, vacuum leaks in the system can impact boost pressure and potentially trigger related codes. The noted -10hg boost gauge reading confirms a leak.
- Software/ECU Issues: In rare cases, a software glitch or problem with the Engine Control Module (ECU) might contribute to the fault. The intermittent “No ECU Communication” fault (code 01314) supports this possibility.
Troubleshooting Steps
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Verify Wiring and Connections: Thoroughly inspect the wiring harness connected to the N249 valve for any visible damage, loose connections, or corrosion. Pay close attention to areas where the wiring might have been disturbed during the recent engine work. Consider the aftermarket 038 Motorsports harness installation and its potential connection issues, specifically pin 7 and the grounded brown wire.
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Test the N249 Valve: Using a multimeter, check the resistance across the valve terminals according to the manufacturer’s specifications. An open circuit reading confirms a faulty valve.
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Check for Vacuum Leaks: Inspect all vacuum hoses and connections for leaks. A smoke test can be beneficial in identifying hard-to-find leaks.
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Address Other Fault Codes: The VCDS scan reveals numerous other faults. Resolving these, particularly the coolant temperature sensor (G2) fault (code 01039), and the intermittent ECU communication issue (code 01314), is crucial. These can contribute to hard starting and potentially mask the root cause of the N249 issue.
Conclusion
The 17695 VCDS code in your Audi TT 1.8T points to a problem with the N249 boost pressure control valve circuit. By systematically investigating the wiring, testing the valve, checking for vacuum leaks, and addressing other related fault codes, you can pinpoint the cause and get your TT back on the road. Remember to consult a repair manual for specific wiring diagrams and testing procedures for your model year. If the problem persists after these steps, professional diagnostics may be necessary.
