Do not driveMinutes
J1939 code SPN 4814. No factory wording for it in the reference — below is the standard meaning of FMI.
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
The engine is already past its temperature limit. An aluminium head goes fast: first the geometry warps, then the gasket burns through.
Next comes a blown head gasket, a damaged head and, at worst, a cracked block. Shut it down and let it cool — never open the expansion tank cap while hot.
Let the engine cool — never open the expansion tank cap while hot. Then check the level and the hoses.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.