The RAM 2500 with the 6.7L Cummins turbo-diesel is a heavy-duty workhorse, equipped with a comprehensive instrument cluster designed to keep you informed of critical engine and emission systems. Due to its high-torque diesel engine, the warning lights emphasize diesel-specific components like the exhaust aftertreatment, glow plugs, and DEF system.
RAM Cummins 2500 Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Check Engine (MIL) | AMBER | The powertrain control module has detected a fault in the engine or emission system specific to the Cummins 6.7L, which may affect performance or emissions compliance. | Use a scan tool to read the diagnostic trouble code; the truck may enter limp mode if severe. | |
| Glow Plug / Preheat | AMBER | Indicates the glow plugs are actively preheating the combustion chambers for cold starts on the Cummins diesel; the light turns off when ready to crank. | Wait until the light extinguishes before starting the engine. | |
| Water in Fuel | RED | The water-in-fuel sensor on the Cummins fuel filter/water separator has detected water accumulation, which can damage the high-pressure fuel system. | Drain the water from the fuel filter/water separator immediately; see owner's manual for procedure. | |
| DPF / Regeneration | AMBER | The diesel particulate filter is actively regenerating to burn off accumulated soot, which is normal for the Cummins aftertreatment system. | Drive at highway speeds if possible to complete regeneration; no immediate action needed. | |
| DEF / AdBlue | AMBER | Diesel Exhaust Fluid level is low or there is a fault in the SCR system, which can lead to derated engine power and eventual no-start if ignored. | Top up DEF with at least 2.5 gallons of approved fluid; if light persists, service the DEF system. | |
| Master Warning (Stop) | RED | A critical condition has been detected requiring immediate engine shutdown to prevent catastrophic damage specific to the Cummins 6.7L. | Pull over safely and shut off the engine; call for roadside assistance. | |
| Master Caution | AMBER | A non-critical but important system alert is active on your RAM 2500; check the message center for details. | Check instrument cluster display for specific warning; schedule service soon. | |
| Battery / Charging | RED | The battery is not being charged properly, often due to a failed alternator on the Cummins or a loose belt. | Immediately check alternator belt and connections; if light stays on, have charging system inspected. | |
| Engine Oil Pressure | RED | Engine oil pressure is below safe levels for the high-torque Cummins, risking severe internal damage. | Stop engine immediately; check oil level and top off if needed; do not restart until resolved. | |
| Coolant Temperature | RED | Engine coolant is overheating, which can cause head gasket failure on the Cummins under heavy load. | Reduce engine load and pull over; let engine idle to cool; check for leaks or low coolant. | |
| Transmission Temp | RED | Transmission fluid temperature is too high, often due to heavy towing or low fluid in the 68RFE or Aisin transmission of the RAM 2500. | Pull over and let the transmission cool in neutral; reduce load and check fluid level. | |
| Brake System | RED | A fault is detected in the hydraulic brake circuit or low brake fluid, which can compromise stopping ability on this heavy truck. | Check brake fluid level immediately; do not drive until brakes are inspected. | |
| ABS | AMBER | The anti-lock brake system has a malfunction; standard brakes still work but ABS is disabled on the RAM 2500. | Normal braking remains; schedule service to diagnose wheel speed sensor or module. | |
| Reduced Power (Limp Mode) | AMBER | The ECM has limited engine power to protect the Cummins from damage due to a detected fault (e.g., turbo, fuel system). | Reduce speed and avoid heavy loads; diagnose with scan tool; restart may clear transient faults. | |
| High Exhaust Temp (HEST) | AMBER | Exhaust gas temperature is elevated during DPF regeneration or high-load operation on the Cummins; may produce more heat near exhaust. | Continue driving normally; avoid parking over dry grass; light goes out when temp drops. | |
| Low Oil Level | AMBER | Engine oil level is low; the 6.7L Cummins holds 12 quarts but consumption can occur under heavy load. | Check and add oil (5W-40 or 15W-40 as recommended) to the full mark on dipstick. | |
| Low Fuel | AMBER | Fuel level is critically low; running out can introduce air into the Cummins fuel system requiring bleeding. | Refuel as soon as possible; avoid running below 1/4 tank to prevent fuel system issues. | |
| Seat Belt | RED | The driver or passenger seat belt is not fastened; the chime may also sound on the RAM 2500. | Fasten your seat belt immediately; light should go off. | |
| Airbag (SRS) | RED | The supplemental restraint system has a fault; airbags may not deploy in a crash on this RAM 2500. | Have the SRS system diagnosed by a dealer; do not delay service. | |
| Tire Pressure (TPMS) | AMBER | One or more tires are significantly underinflated; the RAM 2500's TPMS monitors each tire pressure. | Check tire pressures and inflate to recommended PSI (typically 60-80 PSI rear). | |
| Power Steering (EPS) | RED | Electric power steering malfunction on models equipped with EPS; steering effort may increase greatly. | Steering may become heavy; drive slowly to a service center for diagnosis. | |
| High Beam | BLUE | High beam headlights are active on your RAM 2500; it indicates the high beams are on. | No action needed; dim when approaching traffic. | |
| Fasten Seat Belt | RED | Occupant seat belt is unbuckled; warning chime will sound on the RAM 2500. | Fasten seat belt immediately. | |
| Parking Brake | RED | Parking brake is engaged or not fully released; this light stays on if the brake is set on the RAM 2500. | Release parking brake fully before driving. |
24 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Coolant Overheating
Common causes
- Low coolant level
- Failed thermostat or water pump
- Clogged radiator from debris or mud
What to do
Stop engine immediately; let cool, then carefully add Mopar coolant (OAT) to the cold fill line; inspect for leaks; if recurring, replace thermostat or water pump.
Low Oil Pressure
Common causes
- Low oil level
- Oil pump failure
- Clogged oil filter or incorrect viscosity oil on Cummins
What to do
Shut off engine; check oil level with dipstick; if OK, have oil pressure sending unit tested; do not restart until pressure verified.
DEF System Failure
Common causes
- DEF contamination or incorrect fluid
- DEF heater or pump failure
- NOx sensor fault
What to do
Top off with approved DEF; if light persists, drive at highway speeds to clear; if still on, dealer may need to reset or replace DEF components.
Water in Fuel
Common causes
- Contaminated diesel fuel
- Failed water separator
- Condensation in fuel tank
What to do
Drain water from the fuel filter/water separator (located on driver side of engine); replace filter if heavily contaminated; use additive to prevent gelling.
Transmission Overheating
Common causes
- Low transmission fluid level
- Overloading or steep grades
- Cooler blockage or failure
What to do
Pull over and let transmission cool in neutral; check fluid level with engine running at operating temp; add ATF+4 if low; reduce load.
Frequently Asked Questions
What does the glow plug light mean on a RAM 2500 Cummins?
The glow plug indicator illuminates when the engine is cold to show the glow plugs are preheating the cylinders for easier starting. Wait until the light goes off (typically a few seconds) before cranking.
Why does my check engine light flash or stay on?
A flashing check engine light on a RAM 2500 with the 6.7L usually indicates a severe misfire or emission system malfunction that could damage the catalytic converter. A steady light is less urgent but still needs diagnosis.
Can I drive with the DPF regen light on?
Yes, the DPF regeneration light means the particulate filter is cleaning itself. The RAM 2500 needs to be driven at highway speeds (above 30 mph) for 20-30 minutes to complete the process; avoid frequent short trips.
What should I do if the water in fuel light comes on?
Drain the water from the fuel filter/water separator immediately. Locate the drain valve on the driver side of the engine, place a container under it, and open until clean diesel flows. If light stays on, replace the filter.
Why does my ABS light stay on after snow?
Snow or ice can temporarily block wheel speed sensors on the RAM 2500, causing the ABS light to stay on. Once the sensors are cleared (often after driving on clean roads), the light should turn off. If it persists, check sensor wiring.
What does the master caution light mean?
The master caution light illuminates together with a message in the instrument cluster display to alert you to a non-critical issue like low washer fluid or a minor sensor fault. Check the display for details and schedule a service visit.