Diagnostic article Generic OBD-II
P2517: Low-side refrigerant sensor voltage is below its valid range
See how this GM P2517 monitor samples a low refrigerant-pressure sensor input and why it cannot establish refrigerant quantity.
Read before applying this article
Documented application
GM 2015 15OBDG01 Hybrid Diagnostics, HCP2 (VICM) low-side refrigerant pressure monitor on physical page 572. Per-model applicability and sensor location are not established here; electrical limits are specific to the documented calibration.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2517 is the low electrical input fault for refrigerant pressure sensor B in the cited GM hybrid controller. The source identifies this as the low-side sensor and sets its lower boundary at 2% of the reference voltage, shown as 0.1 V. That is a signal-validity limit, not a refrigerant-charge specification.
Low voltage does not prove an empty system
A scan tool may translate the voltage into a very low pressure reading. Once the electrical-range check fails, that calculated value cannot by itself establish that refrigerant has leaked away. The monitor does not distinguish every possible sensor, reference, connection or circuit fault, and it provides no instruction to add refrigerant.
The controller requires system voltage above 10.2 V. Its decision uses 16 failing samples out of 20 at 100-millisecond intervals, followed by a two-trip Type B illumination strategy. This sampled history is more informative than treating one low reading as the entire failure criterion.
Separate circuit validity from pressure response
P2516 tests whether low-side pressure changes after compressor operation, but P2517 inhibits that performance test. Clearing the low-voltage code without establishing valid input therefore leaves the response assessment incomplete.
Preserve the pressure-sensor voltage, system-voltage context and companion faults before relying on pressure trends. Verification should show that the electrical monitor passed and, when applicable, that the separate performance monitor could run. The source does not establish the sensor's physical location or a safe refrigerant service procedure; use vehicle-specific information and qualified equipment for those tasks.
Source and applicability
GM 2015 15OBDG01 Hybrid Diagnostics, HCP2 (VICM) low-side refrigerant pressure monitor on physical page 572. Per-model applicability and sensor location are not established here; electrical limits are specific to the documented calibration.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
A/C Refrigerant Pressure Sensor B Circuit Low
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT