Cummins fault code 1943
Ambient Air Density: reading below normal (least severe)
What it means
Cummins' description: Ambient Air Density - Data Valid But Below Normal Operating Range - Least Severe Level.
SPN 3555 is Ambient Air Density. FMI 17 means the value is somewhat below normal. It's the mildest 'low' level, often an early warning.
These sensors measure the air coming into the engine: intake manifold temperature, charge air cooler outlet temperature, ambient temperature, barometric pressure, humidity and air filter restriction. The ECM uses them to calculate fueling and timing.
What the lamp means
This code normally doesn't turn on a dash lamp. It's logged in the ECM for a technician to see, and often explains another active code.
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 one-time sensor code with normal power and temperatures.
Schedule a repair
Amber lamp, rough cold starts, or the code returns. Usually a sensor or connector. Book it so fueling stays correct.
Stop and get help
Several sensor codes at once with a stop lamp or no-start. That can point to a shared sensor supply or ECM problem. Get it diagnosed before driving.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Clogged air filter
- Dirty or blocked charge air cooler or radiator fins
- Real high intake temperature in hot weather or under heavy load
- Boost leak changing intake readings
What you can check before calling
- Check the air filter and the restriction indicator
- Clean bugs and debris from the front of the charge air cooler
- Look for unplugged or damaged connectors on intake sensors
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
Listed by Cummins for: 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.
Related Intake air and environment sensors codes
- 2398 SPN 171 FMI 2
Ambient Air Temperature: erratic or intermittent signal - 2571 SPN 2630 FMI 3
Engine Charge Air Cooler Outlet Temperature: circuit voltage high / shorted high - 2572 SPN 2630 FMI 4
Engine Charge Air Cooler Outlet Temperature: circuit voltage low / shorted low - 2964 SPN 105 FMI 15
Intake Manifold 1 Temperature: reading above normal (least severe) - 3341 SPN 107 FMI 16
Engine Air Filter Differential Pressure: reading above normal (moderately severe) - 3367 SPN 4490 FMI 9
Specific Humidity Sensor: abnormal update rate
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 1943 mean?
Cummins fault code 1943 is J1939 SPN 3555 FMI 17: Ambient Air Density - Data Valid But Below Normal Operating Range - Least Severe Level. In plain terms: ambient air density: reading below normal (least severe).
Can I keep driving with Cummins code 1943?
Usually, yes. This code doesn't normally turn on a lamp by itself, but check for other active codes that might be more serious. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 1943?
SPN 3555 identifies the part or system (Ambient Air Density). FMI 17 describes the type of failure: reading below normal (least severe).
What usually causes Cummins code 1943?
The most common causes are: clogged air filter; dirty or blocked charge air cooler or radiator fins; real high intake temperature in hot weather or under heavy load.
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.