Tier 4 Final Lamps and Operation

Cummins Tier 4 Final/Euro Stage IV off-highway engines require little to no operator interaction. Under certain circumstances, an operator-initiated Exhaust System Cleaning may be needed. Exhaust System Cleaning Lamps on the instrument panel light up to show system status.

These engines also require Diesel Exhaust Fluid (DEF), known as AdBlue® in Europe. DEF Lamps indicate when the DEF tank needs to be filled, as does the DEF gauge, located on the dash, alerting the operator when action is needed.

Diesel Exhaust Fluid (DEF) Lamps


DEF Lamp
Illuminates when DEF level is low, and flashes when the DEF falls below a very low level. Operator should refill the DEF tank with DEF.



DEF Lamp With Check Engine Lamp
Illuminates when the DEF level is critically low. If the tank is not refilled immediately, power will be reduced. Operator should refill the DEF tank with DEF. Normal engine power will be restored after the DEF tank is refilled.


Flashing DEF Lamp With Check Engine Lamp
Illuminates when the DEF level is near zero. If the tank is not refilled immediately, power will be further reduced. Operator should refill the DEF tank with DEF. Normal engine power will be restored after the DEF tank is refilled.


Flashing DEF Lamp With Stop Engine Lamp
Illuminates when the DEF gauge has read zero for 30 minutes. Power will be limited to idle. Operator should stop the equipment when it is safe to do so, and refill the DEF tank. Normal engine power will be restored after the DEF tank is refilled.



Exhaust System Cleaning Lamps

HEST lampHigh Exhaust System Temperature (HEST) Lamp
May illuminate due to higher-thannormal exhaust temperature during Exhaust System Cleaning. Operator should ensure that the exhaust pipe outlet is not directed at any flammable or combustible surfaces.

Exhaust lampExhaust System Cleaning Lamp
Illuminates when the exhaust system is unable to complete an automatic Exhaust System Cleaning event. Operator should ensure the Exhaust System Cleaning Switch is not in the “STOP” position and continue working until there is an opportunity, such as at the end of the work day or shift, to complete a stationary Exhaust System Cleaning.

Check engine and exhaust lampExhaust System Cleaning Lamp With Check Engine Lamp
If an Exhaust System Cleaning is not performed in a timely manner after the Exhaust System Cleaning Lamp is illuminated, the Check Engine Lamp will illuminate and engine power will be significantly reduced. Park the equipment when safe to do so, and press the Exhaust System Cleaning Start Switch. Once the cleaning is complete, full engine power will be restored.
Exhaust lampExhaust System Cleaning Lamp
Flashes when a stationary Exhaust System Cleaning event is initiated using the Exhaust System Cleaning Start Switch. This lamp will continue to flash until the stationary cleaning event is complete. Once the lamp turns off, the operator can resume normal work activity.

Exhaust system stop lampExhaust System Cleaning Stop Lamp
Illuminates when the Exhaust System Cleaning Switch is in the “STOP” position, preventing a cleaning event. This switch should be used only when high exhaust temperatures present a hazard. Excessive use of the Exhaust System Cleaning Switch in the “STOP” position will result in the need for more frequent stationary exhaust cleaning events.

Stop engine lampStop Engine Lamp (QSG12 and QSX15 only)
Illuminates when continued operation could result in damage to the exhaust system. Shut down the engine as soon as it is safe to do so, and call for service, or risk damage to the exhaust system.


Exhaust System Cleaning Switch

Tier 4 Exhaust system switchExhaust System Cleaning Enabled
The switch remains in the standard mid-position during normal operations. This means Exhaust System Cleaning is enabled and allows the exhaust system to clear any build-up by initiating automatic cleaning. Exhaust System Cleaning initiated automatically by a preset timer at 20-hour intervals and takes around 15-30 minutes to complete. No operator action is required and the equipment continues to work as normal during the cleaning.

The HEST lamp may illuminate during cleaning to indicate higher than normal exhaust temperatures and safety considerations apply.

Start Exhaust System Cleaning
Pressing the switch into the top position starts a manual (parked) Exhaust System Cleaning . This is required on  infrequent occasions due to very unusual duty cycle conditions. A manual (parked) Exhaust System Cleaning may be needed when the Exhaust System Cleaning Lamp illuminates. When the Start Switch is pressed, cleaning begins and this is confirmed by the Exhaust System Cleaning Lamp flashing.

The HEST lamp may illuminate during the manual (parked) Exhaust System Cleaning  to indicate higher than normal exhaust temperatures and safety considerations apply. The switch returns to the standard Mid-Position after pressing the manual (parked) Exhaust System cleaning.

Stop Exhaust System Cleaning Function
Pressing the switch into the bottom position prevents Exhaust System Cleaning from occurring. Stopping the Exhaust System Cleaning function is required only for safety reasons to avoid higher than normal exhaust temperatures.

When the switch is pressed the Exhaust System Cleaning STOP Lamp illuminates  to indicate Exhaust System Cleaning is disabled. The switch remains engaged in this position until pressed back to the standard mid-position to restore the automatic Exhaust System Cleaning function.

Exhaust System Cleaning should not be left disabled for long periods of time as this results in the need for a manual (parked) Exhaust System Cleaning.