A/C Request B Circuit Low
The P2523 code means the vehicle's onboard diagnostic system has detected: A/C Request B Circuit Low. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
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What Are the Symptoms of P2523?
- Rear A/C compressor request not reaching ECM
- Rear cabin not cooling
- Check engine light on
- Rear A/C controls unresponsive
What Causes P2523? (Most Likely First)
- Short to ground in rear A/C request wiring Very High
- Failed rear A/C control panel High
- Damaged wiring under vehicle or in pillars Moderate
- ECM B circuit input pulled low Low
Can I Still Drive with P2523?
Yes, but fix soon. P2523 is rated low severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
Can I fix P2523 myself?
If you can access the wiring and have basic electrical diagnostic skills, checking for shorts to ground is straightforward. The rear A/C control panel may need professional diagnosis.
Where does the rear A/C wiring typically run?
It usually runs through the C-pillar or along the rocker panel under carpet, areas prone to water damage, abrasion, and rodent damage.
Does P2523 affect front A/C operation?
No. The front A/C system operates on a separate request circuit and should function normally regardless of P2523.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2523?
-
Measure B circuit signal voltage at ECM connector
-
Test rear A/C request wire for shorts to ground
-
Inspect wiring routing through door pillars and under carpet
-
Check rear A/C control panel output signal
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Which Vehicles Commonly Get P2523?
- 2010-2020 Toyota Highlander
- 2012-2019 Honda Pilot
- 2008-2018 Ford Explorer
- 2011-2020 Chevrolet Tahoe
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