Do not driveTo the nearest safe stop
J1939 code SPN 871. Below — how the fault is worded at the factory by International, and what the second half of the code (FMI) means in the standard.
| FMI 1 | Refrigerant Charge — AC - Service now Very low charge |
| FMI 18 | Refrigerant Charge — AC - Service now low charge |
| SPN 871 FMI 1871/1 · 871.1 | data below normal range (most severe level) |
| SPN 871 FMI 18871/18 · 871.18 | below normal — moderate severity |
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
The code is flagged critical: the manufacturer considers it unsafe to keep driving without checking.
This code alone cannot say what will fail next, so stop at the first safe opportunity and look at it on the spot.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.