Cummins fault code 3498
DEF Tank Level: reading below normal (moderately severe)
What it means
Cummins' description: Aftertreatment 1 Diesel Exhaust Fluid Tank Level - Data Valid But Below Normal Operating Range - Moderately Severe Level.
SPN 1761 is Aftertreatment 1 Diesel Exhaust Fluid Tank Level. FMI 18 means the value is clearly below normal operating range. It's the middle 'low' level.
DEF is sprayed into the exhaust ahead of the SCR catalyst to break down NOx. The system includes the tank, level and temperature sensors, a quality sensor, heaters for cold weather, a pump or dosing unit, lines and the doser.
What the lamp means
A blinking amber lamp usually relates to emissions system warnings such as DEF or SCR inducement. Ignoring it can lead to a speed or power derate.
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
The DEF level warning is on and the truck runs normally. Topping off with fresh DEF clears it.
Schedule a repair
Amber lamp or a DEF quality or dosing code that comes back after filling. Get it checked soon. If left alone, the system will start counting down toward a derate.
Stop and get help
Blinking lamp with a derate countdown, or the truck is already limited to low speed. That's an EPA inducement. It won't fix itself and it can leave a truck stuck at 5 mph.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- DEF tank low or empty
- Contaminated, diluted or old DEF (water, coolant, diesel, or DEF older than about a year)
- Crystallized DEF clogging the doser, lines or filter
- Weak pump or blocked DEF filter
- Frozen DEF with a heater not working
What you can check before calling
- Check the DEF level and top off with fresh, sealed DEF
- Look for white crystal buildup around the doser, lines and tank
- If DEF was recently added, think about whether it could have been mixed with water or something else
- Note whether the code shows up only in cold weather
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: DEF warning lights and derate: what diesel drivers need to know.
Engines and sources
Listed by Cummins for: QSB 6.7, QSL 9, QSX 15, QSB 4.5, QSF 3.8 (With SCR), 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
- 1668 SPN 1761 FMI 4
DEF Tank Level Sensor Circuit: circuit voltage low / shorted low - 1669 SPN 1761 FMI 3
DEF Tank Level Sensor Circuit: circuit voltage high / shorted high - 1673 SPN 1761 FMI 1
DEF Tank Level: reading below normal (most severe) - 1699 SPN 1761 FMI 2
DEF Tank Level Sensor: erratic or intermittent signal - 3497 SPN 1761 FMI 17
DEF Tank Level: reading below normal (least severe) - 4677 SPN 1761 FMI 9
SAE J1939 Multiplexing PGN Timeout Error: abnormal update rate - 4679 SPN 1761 FMI 5
DEF Tank Level Sensor Circuit: circuit open / current low - 4732 SPN 1761 FMI 13
DEF Tank Level Sensor: out of calibration
Related DEF codes
- 3558 SPN 3361 FMI 3
DEF Dosing Unit: circuit voltage high / shorted high - 3559 SPN 3361 FMI 4
DEF Dosing Unit: circuit voltage low / shorted low - 3562 SPN 5491 FMI 3
DEF Line Heater Relay: circuit voltage high / shorted high - 3563 SPN 5491 FMI 4
DEF Line Heater Relay: circuit voltage low / shorted low - 3567 SPN 5394 FMI 5
DEF Dosing Valve: circuit open / current low - 3568 SPN 5394 FMI 7
DEF Dosing Valve: not responding / out of adjustment
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 3498 mean?
Cummins fault code 3498 is J1939 SPN 1761 FMI 18: Aftertreatment 1 Diesel Exhaust Fluid Tank Level - Data Valid But Below Normal Operating Range - Moderately Severe Level. In plain terms: def tank level: reading below normal (moderately severe).
Can I keep driving with Cummins code 3498?
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 3498?
SPN 1761 identifies the part or system (Aftertreatment 1 Diesel Exhaust Fluid Tank Level). FMI 18 describes the type of failure: reading below normal (moderately severe).
What usually causes Cummins code 3498?
The most common causes are: dEF tank low or empty; contaminated, diluted or old DEF (water, coolant, diesel, or DEF older than about a year); crystallized DEF clogging the doser, lines or filter.

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