Common Peterbilt Truck Problems and How to Fix Them

Peterbilt trucks are known for their durability, performance, and reliability. However, even the toughest rigs on the road encounter issues over time. Whether electrical failures, after-treatment system malfunctions, or transmission troubles, understanding these problems and how to fix them can help prevent costly downtime. Below, we break down the most common Peterbilt truck problems and the best solutions to keep your truck running efficiently.

1. Electrical System Failures

The Problem:

Peterbilt trucks, particularly newer models with advanced electronic systems, often experience electrical issues. Many drivers report intermittent power loss in gauges, unresponsive dashboard controls, and truck lighting system problems. Some trucks fail to start despite a fully charged battery, often traced back to wiring issues or failing sensors.

Common symptoms of electrical failure include:

• Power loss in dashboard controls, lights, or gauges
• Difficulty starting the truck
• Random warning lights appear on the dashboard

The Fix:

• Check the battery terminals for corrosion and ensure all connections are tight.
• Inspect the wiring harness for damage, especially in high-vibration areas where wires tend to fray or loosen.
• Use a diagnostic scanner to retrieve fault codes and identify failing sensors.
• Test the alternator and starter motor to confirm they are functioning properly.

Regular electrical system inspections and battery maintenance can help prevent these problems before they escalate into significant failures.

2. DPF & After-Treatment System Problems

The Problem:

Peterbilt trucks are equipped with advanced after-treatment systems to comply with emissions regulations. However, components such as the Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) system frequently cause problems. DPF clogging, failed regenerations, and DEF system malfunctions are among the most reported issues.

Common signs of after-treatment failures include:

• Reduced engine power (limp mode)
• Frequent or failed regeneration cycles
• DEF system faults or freezing in cold temperatures

The Fix:

• Perform forced regeneration if the system fails to clean the DPF automatically.
• Inspect the DPF filter and clean or replace it if it is clogged beyond repair.
• Use high-quality DEF fluid to prevent contamination and freezing.
• Check DEF doser injectors for clogging and verify that the SCR system functions correctly.

Running the truck at highway speeds regularly helps burn off excess soot, reducing the need for frequent regenerations and extending the life of the DPF.

3. Transmission & Clutch Issues

The Problem:

Peterbilt trucks, particularly those equipped with automated manual transmissions (AMTs) such as the Eaton Fuller Ultrashift, can experience gear-shifting issues. Many drivers report hard shifting, gear slippage, and difficulty engaging certain gears.

Common symptoms of transmission failure include:

• Grinding noises when shifting gears
• The truck getting stuck in neutral or failing to shift out of gear
• Sluggish acceleration or jerky gear changes

The Fix:

• Check transmission fluid levels and ensure the correct type is used. Low or contaminated fluid can cause shifting issues.
• Inspect the clutch linkage for wear and adjust it if needed.
• If equipped with an AMT, recalibrate the transmission control module (TCM) to reset shift points.
• Replace worn clutch plates if excessive slippage is detected.

Routine transmission maintenance, including regular fluid changes and inspections, can prevent many of these issues from developing.

4. Turbocharger Failures

The Problem:

Turbocharger failures are particularly common in Peterbilt trucks equipped with PACCAR MX-13 engines. A failing turbo can lead to significant power loss and reduced fuel efficiency.

Warning signs of turbo failure include:

• Loss of power, especially when climbing hills
• Excessive smoke from the exhaust (black or blue)
• A high-pitched whining noise from the turbo

The Fix:

• Inspect for boost leaks by checking the intercooler piping and clamps.
• Clean or replace the turbo actuator, as faulty actuators can prevent proper boost pressure.
• Look for excessive oil in the intake piping, which may indicate blown turbo seals.
• Regularly replace air filters to prevent debris from damaging the turbo blades.

Allowing the turbo to cool down before shutting off the truck can extend its lifespan and reduce the risk of premature failure.

5. Overheating & Cooling System Failures

The Problem:

Overheating is a common problem in Peterbilt trucks, especially when hauling heavy loads or operating in high-temperature environments. A malfunctioning cooling system can lead to catastrophic engine damage if not addressed promptly.

Common overheating symptoms include:

• Rising engine temperature under load
• Visible coolant leaks
• Fan clutch failure causing insufficient cooling

The Fix:

• Check coolant levels regularly and top off with the correct type of coolant.
• Inspect the radiator and cooling fan for debris buildup and clean or replace them if necessary.
• Test the thermostat and water pump to ensure they are functioning correctly.
• Verify fan clutch engagement, as a non-working fan can lead to overheating.

Routine coolant system maintenance, including periodic flushing, prevents scale buildup and improves heat dissipation.

6. Suspension & Steering Problems

The Problem:

Rough roads and heavy loads significantly strain a truck’s suspension and steering system. Over time, components such as bushings, kingpins, and air suspension bags wear out, leading to steering instability and uneven tire wear.

Common symptoms include:

• Loose or unresponsive steering
• Uneven or excessive tire wear
• A rough or bouncy ride

The Fix:

• Inspect suspension bushings and kingpins for wear and replace them as necessary.
• Check air suspension bags and airlines for leaks.
• Get a front-end alignment to correct steering pull and tire wear issues.

Regular suspension inspections can help detect issues early and prevent costly repairs.

7. Fuel System Failures

The Problem:

Fuel system problems in Peterbilt trucks often stem from faulty fuel injectors, clogged fuel filters, or fuel pump failures. These issues can lead to poor engine performance, hard starts, or even engine failure if not addressed.

Symptoms of fuel system issues include:

• Hard starting or failure to start
• Rough idling and loss of power
• Increased fuel consumption

The Fix:

• Regularly replace fuel filters to prevent clogging.
• Inspect fuel lines for leaks or damage.
• Test fuel injectors for clogging or malfunction and replace them if necessary.
• Check the fuel pump for proper operation, as a failure can cause fuel delivery issues.

High-quality diesel fuel and additives can help keep the fuel system clean and functioning correctly.

Final Thoughts

Keeping a Peterbilt truck in top shape requires a proactive approach to maintenance and repairs. Whether dealing with electrical failures, after-treatment system malfunctions, turbo problems, or transmission issues, early detection and timely intervention can save truck owners thousands of dollars in costly repairs.

Regular maintenance checks, proper fluid management, and addressing minor problems before they escalate will ensure a long service life for Peterbilt trucks.

If you are in Rigby, ID, and need professional diesel repair services, IBEX Diesel Repair is ready to help. Contact us today to schedule maintenance or repairs for your Peterbilt truck.