P2521 Possible Causes
- Low refrigerant
- Too much refrigerant
- Faulty low pressure sensor
- Low pressure sensor side harness is open or shorted
- Poor electrical connection in low pressure sensor circuit
How to Fix Code P2521
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Check Engine Light illuminated (or Service Engine Soon warning light)
P2521 Meaning
The Powertrain Control Module (PCM) monitors refrigerant pressure through the A/C pressure sensor. The PCM provides a 5V reference and a low reference to the sensor. Changes in A/C refrigerant pressure cause the sensor signal to the PCM to vary. When pressure is high, the signal is high. When pressure is low, the signal is low. The PCM sets the OBDII code when the sensor signal falls outside factory specifications.