Why does my diesel have a misfire?

Your diesel could have a misfire due to a faulty fuel injector. Your fuel injector can fail due to do contaminated or bad fuel. Dirty engine oil on certain models, electrical failure or a mechanical failure of the injector. To know why we need to run tests to determine why you have a misfire and to prevent potential engine damage. 


We start with scanning the ECM for diagnostic trouble codes this tells us if the ECM recognizes the issue as a misfire or as an electrical issue. From there we then will either check electrical connections or take a fuel sample. The wiring harnesses for some fuel injectors can come unplugged causing a misfire. The wiring harness can also become damaged due to rubbing or other damage such as rodents. Sometimes this can be repaired, other times it will need to be replaced. 


When we take a fuel sample, we check for water contamination and other possible contaminates. To determine if the low-pressure fuel system is working properly, we test to make sure it has the correct pressure and flow rate/volume. If this test comes back with low pressure and or flow rate it could be that your misfire is a secondary issue and you have a fuel supply issue as well. Anything that causes fuel starvation can damage the fuel injectors. 


Give us a call and let us take care of you.


Happy Adventures,


Heather

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By jhautoinc February 3, 2026
You want this to work properly.
By jhautoinc January 30, 2026
These are vital to keep you safe on the road.
By jhautoinc January 27, 2026
Your engine will thank you.
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It's more often than you think.