The Peterbilt 348 is a versatile medium-duty truck designed for vocational applications such as construction and delivery. Its instrument cluster is tailored to provide critical alerts for both engine and auxiliary systems, ensuring optimal performance and safety on the job site.
Peterbilt 348 Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Check Engine (MIL) | AMBER | The Check Engine light on your Peterbilt 348 indicates a fault in the engine management system, often related to emissions or sensor performance. | Perform a diagnostic scan with a compatible tool to retrieve the fault code and address the issue promptly. | |
| Brake System | RED | This light warns of a malfunction in the brake system, such as low air pressure or hydraulic issues, critical for safe operation of your Peterbilt 348. | Stop the vehicle safely and inspect brake fluid levels or air pressure; consult your service manual before continuing. | |
| ABS | AMBER | The ABS indicator on the Peterbilt 348 alerts you to a problem with the anti-lock braking system, which may affect traction control. | Have the ABS system inspected by a qualified technician as soon as possible to ensure proper braking performance. | |
| Parking Brake | RED | This red light indicates the parking brake is engaged on your Peterbilt 348; it must be released before moving the truck. | Release the parking brake and ensure the light extinguishes before driving. | |
| Glow Plug / Preheat | AMBER | The glow plug light illuminates when the engine needs preheating for cold starts, common on the Peterbilt 348's diesel engine. | Wait for the light to turn off before starting the engine to ensure proper ignition. | |
| DPF / Regeneration | AMBER | This light indicates that the diesel particulate filter is undergoing or requires active regeneration to clear accumulated soot. | Drive at highway speeds if safe, or perform a stationary regeneration as per the Peterbilt 348 operator's manual. | |
| DEF / AdBlue | AMBER | The DEF level light warns of low diesel exhaust fluid, which can reduce engine performance and eventually prevent starting in the Peterbilt 348. | Refill the DEF tank with approved fluid immediately to avoid speed limitations or engine shutdown. | |
| Water in Fuel | AMBER | This indicator signals that water has accumulated in the fuel filter/water separator, which can cause injector damage in your Peterbilt 348. | Drain the water from the separator as instructed in the vehicle manual, or replace the filter if necessary. | |
| Low Fuel | AMBER | The low fuel light reminds you to refuel the Peterbilt 348 to avoid running out of diesel, which could introduce air into the fuel system. | Fill up at the nearest station; do not let the tank run completely empty. | |
| High Beam | BLUE | This blue light confirms that the high beam headlights are activated on your Peterbilt 348. | Dim your high beams when approaching oncoming traffic to avoid dazzling other drivers. | |
| Seat Belt | RED | The seat belt reminder alerts you that the driver's seat belt is not fastened in the Peterbilt 348. | Fasten your seat belt immediately for your safety; the chime will stop once buckled. | |
| Airbag (SRS) | RED | The airbag light indicates a fault in the supplemental restraint system, which may prevent airbag deployment in a collision. | Have the SRS system diagnosed by a certified technician; do not attempt repairs yourself. | |
| Trailer | GREEN | This green light shows that the trailer is properly connected and the electrical supply is active on the Peterbilt 348. | No action needed unless the light is flashing or off, which indicates a connection issue. | |
| Air Brake Pressure (Low) | RED | The low air brake pressure warning indicates insufficient air pressure for safe brake operation on your Peterbilt 348. | Stop immediately and allow the air compressor to build pressure; if the light persists, park and call for service. | |
| Engine Oil Pressure | RED | Low oil pressure can cause severe engine damage in the Peterbilt 348; this light requires immediate attention. | Stop the engine and check oil level; if level is adequate, do not restart and tow to a repair facility. | |
| Battery / Charging | RED | The battery light signals a problem with the charging system, such as a failing alternator or loose belt on your Peterbilt 348. | Check battery connections and alternator belt; if the light remains on, have the electrical system tested. | |
| Coolant Temperature | RED | An overheated engine can cause catastrophic failure in the Peterbilt 348; this light warns of high coolant temperature. | Pull over safely, let the engine idle, and check coolant level; do not remove the radiator cap while hot. | |
| Transmission Temp | RED | High transmission temperature can damage the gearbox on your Peterbilt 348, especially under heavy load. | Stop and let the transmission cool; reduce load or drive at lower speeds if recurring. | |
| Tire Pressure (TPMS) | AMBER | The TPMS indicator warns of low tire pressure in one or more tires on the Peterbilt 348, affecting fuel economy and safety. | Check and inflate tires to the recommended pressure; inspect for punctures if the light stays on. | |
| Reduced Power (Limp Mode) | AMBER | The reduced power light indicates the engine has entered limp mode to prevent damage, limiting speed and torque on your Peterbilt 348. | Drive to a safe location and have the engine system diagnosed; common causes include high exhaust temps or sensor failures. |
20 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Engine Overheat
Common causes
- Low coolant level
- Faulty thermostat
- Radiator blockage
What to do
For the Peterbilt 348, check coolant level in the degas bottle and inspect for leaks; if overheating persists, have the cooling system serviced by a dealer.
Air Brake Failure
Common causes
- Compressor fault
- Air line leak
- Governor malfunction
What to do
On your Peterbilt 348, stop immediately if air pressure drops below 60 psi; inspect air lines for leaks and have the air system repaired before driving.
Transmission Overheat
Common causes
- Low transmission fluid
- Excessive load
- Cooler blockage
What to do
For the Peterbilt 348, pull over and let the transmission cool; check fluid level and ensure the auxiliary cooler is clean if equipped.
DPF Clogged
Common causes
- Frequent short trips
- Failed regeneration
- Excessive idling
What to do
On the Peterbilt 348, perform a stationary regeneration if safe; if the light stays on, the DPF may need professional cleaning or replacement.
DEF System Malfunction
Common causes
- Low DEF quality
- Faulty injector
- Heater failure
What to do
For the Peterbilt 348, refill with fresh DEF and check for leaks; if the light remains, the system may require dealer service to restore engine power.
Frequently Asked Questions
What should I do if the Check Engine light flashes on my Peterbilt 348?
A flashing Check Engine light indicates a severe misfire; reduce speed and load immediately and have the engine diagnosed to prevent catalytic converter damage.
Why does my Peterbilt 348's DPF regeneration light stay on for a long time?
Extended regeneration may occur if the exhaust temperature is too low; try driving at highway speeds for 20 minutes to assist the process, or consult your dealer if it persists.
Can I drive my Peterbilt 348 with the brake system warning light on?
No, this light indicates a serious brake issue; stop safely and do not drive until the problem is resolved, as brake failure could occur.
How often should I check the DEF level in my Peterbilt 348?
Check the DEF gauge daily; refill when it reaches 1/4 tank to avoid triggering reduced power or speed limitations.
What does the glow plug light mean in warm weather?
The glow plug light may still illuminate briefly for preheating, but if it stays on after starting, a glow plug or controller fault may exist; have it inspected.
Is it safe to operate the Peterbilt 348 with the ABS light on?
You can still drive, but the ABS and traction control will be disabled; normal braking remains, but avoid slippery conditions and have the system repaired soon.