E71E

What the Code Means

Code E71E logs a CAN network communication fault tied to the torque request message from the IHKA module (climate control). Normally the IHKA sends a torque request to the DME so the engine control module can pre-compensate for the load from the A/C compressor. If the message is missing or invalid, the code stays in memory. Possible causes are a faulty IHKA module, wiring problems, or DME communication faults on the CAN bus.

Symptoms

• air conditioning doesn't work;
• idle speed fluctuates;
• check engine light is on;
• no communication with the IHKA module during diagnosis.

Diagnosis and Repair

1. Read the network through ISTA and check CAN communication with the IHKA module.
2. Inspect the IHKA module wiring and connectors for damage and corrosion.
3. Check that the IHKA module is working.
4. If the fault is confirmed, replace the IHKA module.

Secondary Problems

• the A/C compressor won't engage — no cabin cooling;
• the DME doesn't compensate for the A/C load — rough idle, up to and including engine stall.