A/C Request Circuit Malfunction
The P2519 code indicates a problem in the A/C request circuit, which is the signal from the A/C control module to the powertrain control module (PCM) requesting compressor engagement. This circuit typically involves a 5V reference signal, ground, and a signal wire. When the PCM detects an abnormal voltage or signal loss, it sets this code. Common causes include a faulty A/C pressure sensor, wiring issues (shorts, opens, corrosion), or a defective PCM. The A/C system may not operate correctly, leading to no cooling or intermittent operation.
01. Most Common Causes
- Faulty A/C pressure sensor
- Open or shorted wiring in the A/C request circuit
- Corroded or loose electrical connectors
- Failed PCM (rare)
02. Symptoms You Will Notice
- A/C compressor does not engage
- No cold air from vents
- A/C works intermittently
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for related codes (e.g., P0530, P0645).
Step 2: Inspect the A/C pressure sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Test the A/C request circuit voltage at the PCM connector with a multimeter (should be 0-5V depending on A/C request).
Step 4: If voltage is out of range, disconnect the A/C pressure sensor and check for 5V reference and ground at the harness side.
Step 5: If wiring and sensor are good, suspect a PCM issue and perform a PCM reflash or replacement if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the A/C will not work. Driving without A/C is safe, but if the code is due to a wiring short, it could affect other systems. It's best to diagnose promptly.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, but if the PCM needs replacement, costs can exceed $500.