DEF Warnings and Engine Limits
Important: Ignoring the DEF warning lights results in limited engine power, with the application of a 5 mph (8 km/h) speed limit.
DEF Level Low—Initial Warning
When the DEF level is low, the following lamps notify the driver. See Fig.. Refill the DEF tank in order to cancel the warning sequence.
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One bar of the DEF level indicator illuminates amber—DEF very low, refill DEF.
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The DEF warning lamp illuminates solid amber.
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DEF Warning Lamp (illuminated)
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DEF Lightbar (one bar amber)
Fig. 1, DEF Level Low Initial Warning
DEF Empty
When the DEF level reads empty, the following lamps notify the driver. See Fig..
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One bar of the DEF level indicator flashes red—DEF empty, refill DEF.
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The DEF warning lamp flashes amber.
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The MIL lamp illuminates.
Pre-2013 Detroit engines: Power is limited, with a 55 mph (90 km/h) speed limit.
Cummins and 2013 Detroit engines: Power is limited with progressively harsher engine power limits applied.
Note: MIL illuminates. CHECK engine lamp illuminates if Cummins ISB or ISC/L engine. Engine power is limited.
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DEF Warning Lamp (flashing)
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DEF Lightbar (one bar flashing red)
Fig. 2, DEF Empty Warning
DEF Tank Empty and Ignored
If the empty warning is ignored and the DEF tank is not refilled, the red STOP engine lamp illuminates in addition to the MIL lamp and CHECK engine lamp (on vehicles with a Cummins ISB or ISC/L engine.) See Fig..
If the DEF is not refilled, a 5 mph (8 km/h) speed limit is applied after the next engine shutdown, while parked and idling, or if a fuel refill is detected.
Note: STOP engine light and MIL illuminate, engine power is limited, speed limit of 5 mph (8 km/h)
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DEF Warning Lamp (flashing)
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DEF Lightbar (one bar flashing red)
Fig. 3, DEF Empty and Ignored Warning
DEF Contamination or SCR Tampering
Notice: Once contaminated DEF or tampering has been detected, the vehicle must be taken to an authorized service facility to check the SCR system for damage and to deactivate the warning lights and engine limits.
If contaminated DEF or tampering with the ATS is detected, the DEF warning light flashes and the MIL lamp illuminates to warn the driver. The CHECK engine lamp also illuminates on vehicles with a Cummins ISB or ISC/L engine. See Fig..
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Detroit engines: Engine power is limited with progressively harsher limits applied. If the fault is not corrected, the STOP engine light illuminates and a 5 mph (8 km/h) speed limit is applied after the next engine shutdown, while parked and idling, or if a fuel refill is detected.
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Cummins engines: Engine power is limited with progressively harsher limits applied. If the fault is not corrected, the STOP engine light illuminates and a 5 mph (8 km/h) speed limit is applied after the next engine shutdown, or while parked and idling.