A/C Refrigerant Pressure Sensor Circuit High
The P2518 code indicates that the A/C refrigerant pressure sensor is sending a voltage signal higher than the expected range to the PCM. This sensor monitors the pressure of the refrigerant in the A/C system. A high voltage reading typically means the sensor is detecting high pressure, which could be due to a faulty sensor, wiring issues, or actual high system pressure. The PCM uses this input to control the A/C compressor and cooling fans. If the signal is out of range, the PCM may disable the A/C compressor to prevent damage.
1. Most Common Causes
- Faulty or internally damaged A/C refrigerant pressure sensor 'B'
- Short to voltage in the sensor circuit wiring
- Corroded, loose, or poor ground electrical connection
- Sensor wiring shorted to the 5-volt reference circuit
- Extreme refrigerant overpressure causing a legitimate out-of-range reading (less common)
- Failed control module (PCM or A/C module)
2. Symptoms You Will Notice
- A/C system inoperative or blows warm air
- A/C compressor clutch not engaging
- Cooling fans running continuously or not at all
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to read the sensor voltage and compare to actual pressure using a manifold gauge set.
Step 2: Inspect the sensor connector and wiring for damage, corrosion, or shorts to power.
Step 3: Test the sensor's reference voltage (typically 5V) and ground at the connector.
Step 4: If voltage is high with low pressure, replace the sensor. If voltage is normal, check for high system pressure or PCM issues.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the A/C will likely not work. Driving without A/C is safe, but if the high pressure is real, it could damage the A/C system. Have it diagnosed soon.
How much does it cost to fix?▼
Typically $50-$150 for a sensor replacement, plus diagnostic time. If wiring repair is needed, costs may be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.