Why is my 2022 Freightliner Cascadia getting 1.5 mpg worse than last month?
A sudden 1.5 mpg drop in a 2022 Freightliner Cascadia usually means a clogged diesel particulate filter, failing fuel injectors, low tire…
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Heavy-Duty Vehicles & Fleet
Practical, step-by-step fixes for heavy-duty vehicles & fleet problems — 67 published so far.
Why is my 2022 Peterbilt 579 burning 15% more fuel since the last dealer visit
A sudden 15% fuel economy drop after dealer service usually means the ECM was reflashed with a calibration that changed injection timing…
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why is my diesel truck burning more fuel than usual all of a sudden?
A sudden jump in diesel fuel use usually comes from something simple: underinflated tires, a clogged air filter, a dragging brake, or…
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Why is my diesel truck burning more fuel than usual?
A diesel truck burning excess fuel usually means a clogged air filter, faulty injectors, low tire pressure, or a malfunctioning turbocharger —…
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Why is my diesel truck getting 2 MPG worse than last month
A sudden 2 MPG drop usually means a clogged fuel filter, failing injectors, low tire pressure, or a stuck EGR valve —…
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Why is my diesel truck getting worse fuel mileage all of a sudden?
Sudden fuel mileage drops in diesel trucks usually stem from a clogged air filter, failing fuel injectors, a stuck EGR valve, or…
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Why is my diesel truck suddenly burning 20% more fuel than last month?
A sudden 20% jump in fuel consumption usually means a clogged air filter, failing fuel injectors, low tire pressure, or a stuck-open…
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Why is my diesel truck suddenly getting worse fuel mileage?
A sudden drop in diesel fuel mileage usually means a clogged fuel filter, faulty injectors, low tire pressure, or a failing turbocharger…
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Why is my diesel truck suddenly using more fuel than normal?
A sudden drop in fuel economy usually means a clogged fuel filter, failing injectors, low tire pressure, or a malfunctioning sensor like…
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Why is my diesel truck throwing a P20EE code and going into derate mode?
A P20EE code means your selective catalytic reduction (SCR) system isn't converting NOx efficiently, usually from contaminated diesel exhaust fluid (DEF), a…
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Why is my diesel truck's DEF system throwing a fault code and limiting engine power?
A DEF system fault with power derate usually means the dosing valve, NOx sensor, or DEF quality sensor has failed, or the…
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Why is my diesel truck's DEF system throwing a P20EE code and going into derate?
A P20EE code means the selective catalytic reduction (SCR) system detects NOx conversion efficiency below threshold, usually from contaminated diesel exhaust fluid…
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