New Holland T4.100 Warning Lights and Symbols (Meaning and Fixes)

Quick answer: These dashboard warning lights follow the ISO 2575 international standard. A red symbol means stop the machine and check immediately, amber or yellow means service soon, and green or blue symbols are normal status indicators. Each symbol below is explained with its meaning, the most likely cause, and the recommended action.

The New Holland T4.100 instrument cluster provides key operational indicators for this compact yet powerful utility tractor, designed for loader work and field tasks. The display alerts you to engine, transmission, and hydraulic system status to ensure safe operation.

How to read the colors: Red symbols indicate critical issues requiring immediate shutdown; amber warns of pending service or caution; green/blue show active systems or normal operation.

New Holland T4.100 Warning Light Symbols

SymbolNameColorWhat it meansWhat to do
Master Warning (Stop)REDIlluminates when a critical fault occurs, such as engine shutdown or brake failure on the New Holland T4.100.Stop the tractor immediately and consult the fault code on the display.
Master CautionAMBERLights up for non-critical warnings like low DEF or transmission temperature approaching limit on your T4.100.Check the message center for details and address the issue soon.
Check Engine (MIL)AMBERIndicates an engine management fault, such as a sensor issue or DPF blockage in the T4.100's FPT engine.Have the engine diagnosed by a dealer; continued operation may reduce power.
Engine Oil PressureREDWarns of low engine oil pressure, which can cause severe engine damage in the New Holland T4.100.Stop the engine immediately and check oil level.
Battery / ChargingREDGlows when the alternator fails to charge the battery, often due to a loose belt on the T4.100.Check the alternator belt and connections; if persistent, seek service.
Coolant TemperatureREDSignals the engine coolant is too high, possibly from radiator blockage or low coolant in the T4.100.Pull over, let engine cool, and check coolant level and fan.
ATTransmission TempAMBERShows the transmission oil is hot, typical during heavy loader work with the T4.100.Reduce load or shift to a higher gear to cool the transmission.
Brake SystemREDIndicates a brake fluid leak or low pressure in the hydraulic brakes of the T4.100.Stop safely and check brake fluid reservoir; do not operate until fixed.
PParking BrakeAMBERReminds you that the parking brake is engaged on the New Holland T4.100, or indicates a sensor fault.Release the parking brake before moving; if light stays on, check switch.
Glow Plug / PreheatAMBERIlluminates briefly when preheating the engine's glow plugs for cold starts on the T4.100.Wait for the light to turn off before starting the engine.
DPF / RegenerationAMBERShows the diesel particulate filter needs regeneration due to soot buildup in the T4.100's exhaust.Drive the tractor at moderate load to initiate automatic regeneration.
Water in FuelAMBERAlerts that water has accumulated in the fuel filter/water separator of the T4.100.Drain the water separator according to the operator's manual.
Low FuelAMBERWarns that the fuel level is low on the New Holland T4.100, typically below 1/8 tank.Refuel soon to avoid running out in the field.
High BeamBLUEActivates when the high-beam headlights are turned on for better visibility at night on the T4.100.Dim when approaching other vehicles or workers.
PTOPTO EngagedGREENIndicates the rear PTO is engaged and rotating at the set speed on the New Holland T4.100.Disengage before servicing or leaving the seat.
Differential LockGREENLights when the differential lock is engaged for improved traction in slippery conditions on the T4.100.Disengage when turning on hard surfaces.
Work LightsGREENShows that the rear or front work lights are turned on for loader or field operations on the T4.100.Turn off when not needed to conserve battery.
Beacon / Rotating LightGREENIndicates the roof-mounted beacon is active for safety when operating near roads on the T4.100.Use during road travel or low visibility.

18 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.

Most Important Warning Lights

Engine Overheat

Common causes

  • Low coolant
  • Clogged radiator fins
  • Faulty thermostat

What to do

Allow engine to cool, clean the radiator exterior, and top off coolant with the correct mixture for the T4.100.

Transmission Overheat

Common causes

  • Excessive loader work
  • Low transmission oil
  • Hydraulic overload

What to do

Shift to a lower gear or reduce load; check transmission oil level and add T4.100-specified fluid.

Engine Won't Start

Common causes

  • Low battery
  • Glow plug failure
  • Fuel system air

What to do

Charge battery, check glow plug relay, and bleed fuel system per the T4.100 manual.

DPF Clogged

Common causes

  • Frequent idle operation
  • Low exhaust temp
  • Sensor malfunction

What to do

Operate tractor under load for 20 minutes to initiate regen; if light persists, dealer service required.

Hydraulic Lift Failure

Common causes

  • Low hydraulic oil
  • Faulty control valve
  • Filter clogging

What to do

Check and refill hydraulic oil to full mark, replace filter, and inspect hoses for leaks on the T4.100.

Frequently Asked Questions

Why does the DPF light stay on while plowing?

Plowing generates high exhaust temps, but if the DPF light stays on, the regeneration may be interrupted. Stop periodically to allow completion, or consult your T4.100 dealer.

How do I reset the service hour meter?

The hour meter is not user-resettable; it tracks cumulative engine hours. Use the display menu to view service intervals, then reset only after dealer service.

Can I operate with the transmission temp light on?

No, stop heavy work immediately. The T4.100's transmission can be damaged if overheated. Let it cool and check oil level.

What does the water in fuel light mean exactly?

It means the fuel filter/water separator contains water that can damage the injection pump. Drain the separator bowl located on the left side of the engine.

Why is the master caution on with no other lights?

Check the digital display for hidden faults like low DEF level or a sensor code. The T4.100 logs multiple parameters; use the menu to scroll warnings.

How do I know if the glow plugs are working?

When the key is turned to ON, the glow plug light should illuminate for 5-10 seconds in cold weather. If it doesn't, the relay or plugs may need inspection.