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Our automotive experts have put together the following information about the P0646 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0646 code.

OBD II Fault Code

  • OBD II P0646

    OBD-II Code A/C may not operate is defined as a A/C Clutch Relay Control Circuit Low

    The engine control module (PCM) uses a relay to control voltage to the A/C Compressor Clutch. The A/C clutch engages, allowing the Air Conditioning system to operate. When the PCM is unable to control the relay, code P0646 will set.

    A/C may not operate Symptoms

    • A/C may not operate

    Common Problems That Trigger the P0646 Code

    • A/C compressor failure
    • A/C compressor relay failure
    • Powertrain Control Module (PCM) failure
    • Wiring issue

    Common Repairs Needed for the P0646 Code

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