P0646 OBD-II: A/C Clutch Relay Control Circuit Low

P0646 Severity

Moderate

Will P0646 go away on its own?

Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.

For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.

Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.

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What causes OBD-II fault code P0646?

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.

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

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

AC Compressor Replacement

OBD Code Resources

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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

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

AC Compressor Replacement

P0646 OBD-II: A/C Clutch Relay Control Circuit Low

Will P0646 go away on its own?

What causes OBD-II fault code P0646?

Need a P0646 diagnosis? Trust our experts.

OBD II Fault Code

A/C may not operate Symptoms

Common Problems That Trigger the P0646 Code

Common Repairs Needed for the P0646 Code

OBD Code Resources

Need a P0646 diagnosis? Trust our experts.

Ask our experts about P0646.

Other OBD-II Codes

OBD II Fault Code

A/C may not operate Symptoms

Common Problems That Trigger the P0646 Code

Common Repairs Needed for the P0646 Code