Engine
    high urgency
    truck

    Why Is My Diesel Truck Losing Power?

    Typical repair cost: $200–$8,000

    Get free quotes for why is my diesel truck losing power? from local shops.

    Describe the job once and compare real bids from nearby verified providers — no phone tag, no obligation.

    Get Free QuotesBrowse Local Providers

    Common Symptoms

    Loss of power under load
    Black or white smoke
    Limp mode / derate
    Check-engine + emissions lights
    Fuel mileage drop

    Most Likely Causes

    1

    Clogged DPF

    Most common cause of derate; needs forced regen or service.

    2

    Failed DEF system / NOx sensor

    Triggers SCR derate; aftertreatment monitor codes.

    3

    Bad turbo / VGT actuator

    Boost code (P0299), whistle, oil in intercooler.

    4

    Plugged fuel filter

    Cheapest fix; should be on PM schedule.

    5

    EGR cooler / valve failure

    Carbon buildup, coolant loss, white exhaust smoke.

    How a Shop Diagnoses It

    1. 1.Pull all modules with a heavy-truck scan tool (J1939) — not just engine.
    2. 2.Check DPF differential pressure and soot load %.
    3. 3.Read boost vs commanded; check VGT operation.
    4. 4.Inspect fuel filter restriction and water separator.

    When to see a professional

    Don't bypass aftertreatment — it's a federal violation and triggers permanent derate. Get it to a diesel shop.

    Find a shop near you

    Diesel Repair Shops
    Browse verified providers
    Truck Repair Shops
    Browse verified providers
    Fleet Service Providers
    Browse verified providers

    Authoritative sources

    Related Engine problems

    Check engine light
    $0–$1200 typical repair
    Oil leak
    $100–$1800 typical repair
    Flashing CEL
    $80–$2000 typical repair
    Engine knocking
    $50–$8000 typical repair
    Rough idle
    $0–$1200 typical repair

    Keep exploring

    DPF Cleaning Cost

    Typical price range

    Turbocharger info

    100,000-180,000 miles (longer with strict oil-change intervals)

    Fuel Injectors info

    100,000-150,000 miles (less on dirty fuel)

    Diesel Particulate Filter (DPF) info

    150,000-300,000 miles (cleanable, eventually replaced)

    All vehicle problems

    OBD-II code lookup

    Repair cost guides

    Fix it yourself or hire a pro

    unknown
    truck

    Parts pros use for this job

    Tools pros use

    Prefer a professional?

    Get free quotes from verified shops near you. Most respond in under 15 minutes — no obligation.

    • ✓Compare written estimates
    • ✓Verified reviews & ratings
    • ✓Book online in 60 seconds

    Product picks are curated by our team based on what shops actually use. Links go to Amazon; as an Amazon Associate we may earn a small commission — it never changes the price you pay.

    Get free quotes from local shops

    Verified providers in your area can give you a written estimate in minutes.

    Related Repair Help

    All Common Problems

    Symptom-based browse

    DTC Code Lookup

    Decode any check-engine code

    Repair Cost Guides

    What the fix should cost

    Find Top-Rated Shops

    Verified pros near you

    Brake Job Cost

    Transmission Replacement Cost

    Auto Repair in Houston, TX

    Auto Repair in Dallas, TX

    Run your shop from estimate to payment

    Turn the work you just looked up into a paid invoice.

    Repairius keeps estimates, work orders, real-time job assignment, customer and vehicle history, inventory, and payments in one place — on desktop and in your pocket.

    Start Your Free TrialSee How Repairius Works

    14-day free trial · credit card required · cancel anytime

    Not a mechanic? Send Repairius to your shop — they can run estimates, jobs, and invoices in one place.

    Know someone who needs this?

    Share this page with a mechanic, a shop owner, or a friend working on the same problem.