Emergency Stop Circuit Open or E-Stop Activated
What does PERKINS-EE mean?
The PERKINS-EE (Kohler RDC2) diesel fault code means: Emergency Stop Circuit Open or E-Stop Activated. This is a serious severity code.
Common Symptoms
- Panel displays EE and the genset refuses to crank or start
- Red fault or shutdown lamp is lit on the controller face
- ATS does not transfer load even during a mains failure event
- Audible alarm sounds continuously until silenced on the panel
- Generator that was running shuts down immediately and will not restart
- AUTO mode appears selected but the genset will not exercise on schedule
- Remote annunciator panel shows an emergency stop condition
Probable Causes (Ranked by Likelihood)
- Remote E-stop mushroom button is physically depressed or latched in the pressed position Very Likely
- E-stop wiring loop is open due to a broken wire, loose terminal, or corroded connection between the panel and the remote stop station Very Likely
- Local panel E-stop button is latched or faulty and not returning to the run-enable position after being released Likely
- Incorrectly wired or missing termination resistor or jumper on an unoccupied E-stop terminal block position Possible
- Water ingress or rodent damage to the E-stop circuit cable run Possible
- Faulty PowerWizard 1.1/2.0 controller input board that reads the E-stop loop as open even when the circuit is intact Less Likely
- Interlock from a remote monitoring system such as OnCue or Mobile Link sending a commanded shutdown that holds the E-stop signal low Less Likely
Step-by-Step Diagnostic Procedure
Start at the most obvious place. Walk around the genset enclosure and look for any mushroom-head red E-stop button that is pushed in and latched. Twist the button clockwise until it pops outward. Do the same for any remote E-stop station wired to the set, including those mounted on walls or transfer switch cabinets.
Check the local panel E-stop button if the unit has one. Press and release it firmly to confirm it is fully in the OUT position. Some buttons require a quarter-turn twist to unlatch. If it feels sticky or does not spring back, the button itself may be faulty.
With the genset in the OFF position, open the controller panel and locate the E-stop terminal block (on PowerWizard controllers this is typically the ES+ and ES- terminals, sometimes labeled ESTOP1 and ESTOP2). Using a multimeter set to DC volts or continuity mode, measure across the two E-stop terminals. A healthy closed loop reads near 0 ohms continuity or the supply reference voltage the controller expects. An open circuit with no continuity confirms the loop is broken somewhere in the wiring.
If continuity is absent, disconnect the external E-stop wiring at the terminal block and install a temporary jumper wire directly across the two terminals. This isolates whether the fault is in the external cable run or inside the controller itself. If the code clears with the jumper in place, the problem is in the field wiring or a remote button, not the controller.
Trace the E-stop cable from the panel to every remote button along the run. Look for pinched conduit, corroded connectors, loose ferrules, or rodent damage. Tug each connector gently. A high-resistance connection that looks intact can still break the loop under vibration.
After you restore or jumper the E-stop circuit, clear the fault. On a PowerWizard 1.1 or 2.0 controller press the STOP button, wait five seconds, then navigate to the fault reset option in the menu and confirm. On FG Wilson DSE-based panels, press and hold the STOP/RESET button until the alarm lamp clears.
Attempt to return the unit to AUTO. If the EE code immediately returns with no button pressed and the loop is confirmed closed, the PowerWizard input board may have a failed input channel. At this point you need Perkins EST (Electronic Service Tool) connected via the service port to read live input states and confirm whether the controller sees the loop as open. Call a certified Perkins or FG Wilson technician.
If the unit is connected to an OnCue or Mobile Link remote monitoring system, log in to the portal and check the event history for any commanded remote shutdown events. A remote shutdown command from the portal can hold the genset off and display as an E-stop condition on some controller revisions.
Frequently Asked Questions
What does the EE code mean on a Perkins or FG Wilson generator?
EE means the controller has detected that the emergency stop circuit is open. Either a physical E-stop button has been pressed and latched, or the wiring loop that connects all the E-stop buttons together has been broken somewhere. The genset interprets either condition as a commanded emergency stop and will not run until the loop is closed and the fault is cleared.
Can my generator still run with the EE code showing?
No. The EE code is a hard shutdown. The genset will not crank in AUTO or MANUAL until the E-stop circuit is restored and the alarm is actively cleared on the controller. If the power goes out while this code is active, the ATS will not receive a start signal and your load will remain without power.
How much does it cost to fix the EE fault?
If a mushroom E-stop button just needs to be twisted and released, the cost is zero. If a wire is broken or a connector is corroded, a DIY repair with basic tools and a few dollars of wire and terminals can solve it. If you need a technician to trace wiring or replace a faulty E-stop button station, expect $150 to $400 in labor. A failed PowerWizard controller input board is the most expensive outcome at $600 or more all in.
Will the generator start the next time the power goes out?
Not while the EE code is active. This is one of the few faults that completely blocks an automatic start. Fix the E-stop circuit, clear the fault, and confirm the unit returns to a READY or AUTO status on the panel before assuming it will respond to a mains failure. Do a manual test run to verify.