P2523 reports that A/C request input B is pulled below its valid range. On the wire level this usually means a conductor grounded against body metal, a sending module whose output transistor has failed shorted, or a wet connector draining the signal. Whether the engine module then assumes a constant request or none depends on the circuit design, and no maker states it publicly; P2523 has no codegenau manufacturer documentation. The regulatory basis is CARB's A/C component monitoring, required only where the A/C changes fuel or spark control. Cars that receive the request over CAN, like the 2011 Saab 9-5, cannot set it. P2522 is the generic circuit fault on B, P2524 the high side, and P2520 the same low fault on input A. Expect missing or unwanted compressor operation.
Low severity. Can I keep driving?Yes, you can keep driving. The air conditioning may not work.
Symptoms
- Compressor not engaging or engaging unasked
- A/C-related idle compensation missing
Most likely causes
- Input B wire shorted to ground
- Output stage of the sending module shorted
- Moisture in a connector of the request line
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
What each character of P2523 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 5: Speed and idle
- 23: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2523?
Yes, you can keep driving. The air conditioning may not work.
What causes code P2523?
The most common causes are: input B wire shorted to ground; output stage of the sending module shorted; moisture in a connector of the request line.
Related codes
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.