Cummins fault code 422
Coolant Level: erratic or intermittent signal
What it means
Cummins' description: Coolant Level - Data erratic, intermittent or incorrect.
SPN 111 is Engine Coolant Level. FMI 2 means the signal is jumping around, dropping in and out, or doesn't make sense compared to other readings.
The cooling system keeps the engine at operating temperature. The ECM watches coolant temperature, pressure and level, and will derate or shut down the engine to protect it from overheating.
What the lamp means
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
A coolant level warning that clears after topping off with the right coolant, and no leak shows up.
Schedule a repair
Coolant keeps dropping, the gauge runs hotter than normal, or the amber lamp is on. Find the leak before it becomes an overheat.
Stop and get help
Temperature gauge in the red, steam, a stop lamp, or engine protection derating power. Pull over and shut it down. Running hot can warp the head and ruin the engine.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Low coolant from a leak
- Radiator or charge air cooler blocked with dirt or bugs
- Fan clutch or fan not engaging
- Stuck thermostat
- Failing water pump
- Head gasket or EGR cooler pushing exhaust into the coolant
What you can check before calling
- Check the coolant level only with the engine cool
- Look for leaks, wet spots or dried coolant residue
- Clean the front of the radiator and charge air cooler
- Watch the temperature gauge and whether the fan kicks on
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers. For the bigger picture, read our guide: Car overheating: what to do right now, and what's causing it.
Engines and sources
Listed by Cummins for: QSX 15, QSG 12. Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
- 195 SPN 111 FMI 3
Coolant Level Sensor 1 Circuit: circuit voltage high / shorted high - 196 SPN 111 FMI 4
Coolant Level Sensor 1 Circuit: circuit voltage low / shorted low - 197 SPN 111 FMI 18
Coolant Level: reading below normal (moderately severe) - 235 SPN 111 FMI 1
Coolant Level: reading below normal (most severe) - 2448 SPN 111 FMI 17
Coolant Level: reading below normal (least severe) - 3366 SPN 111 FMI 18
Coolant Level: reading below normal (moderately severe) - 3613 SPN 111 FMI 9
Coolant Level Sensor: abnormal update rate - 3614 SPN 111 FMI 19
Coolant Level Sensor: network data error
Related Engine cooling codes
- 334 SPN 110 FMI 2
Engine Coolant Temperature: erratic or intermittent signal - 233 SPN 109 FMI 18
Coolant Pressure: reading below normal (moderately severe) - 611 SPN 1383 FMI 31
Engine Shut Down Hot: condition exists - 232 SPN 109 FMI 4
Coolant Pressure Sensor Circuit: circuit voltage low / shorted low - 231 SPN 109 FMI 3
Coolant Pressure Sensor Circuit: circuit voltage high / shorted high - 151 SPN 110 FMI 0
Engine Coolant Temperature: reading above normal (most severe)
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 422 mean?
Cummins fault code 422 is J1939 SPN 111 FMI 2: Coolant Level - Data erratic, intermittent or incorrect. In plain terms: coolant level: erratic or intermittent signal.
Can I keep driving with Cummins code 422?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 422?
SPN 111 identifies the part or system (Engine Coolant Level). FMI 2 describes the type of failure: erratic or intermittent signal.
What usually causes Cummins code 422?
The most common causes are: low coolant from a leak; radiator or charge air cooler blocked with dirt or bugs; fan clutch or fan not engaging.
Diesel down in the Midlands?
We work on Cummins-powered pickups, vans and medium-duty trucks across Lexington, Columbia and the Midlands, on site at your yard or roadside.