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Warning: That 'simple' fuel rail pressure sensor took me 6 hours to find
Had a 2012 Freightliner Cascadia come in last month with a no-start condition and intermittent stalling. Scanned it, got a fuel rail pressure code, and assumed it was the CP4 pump. After swapping the pump and still having the issue, I spent 3 more hours chasing wiring and checking grounds. Turns out it was a bad fuel rail pressure sensor that tested fine cold but failed when warm. Took me 6 hours total for what should have been a 1 hour diagnosis. Has anyone else had a sensor pass a cold test but fail hot?
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grace_campbell2mo ago
Stick with the diesel guys who told me years ago to always check sensors when they're hot first. Heat cycling messes with internals in ways a cold multimeter reading just won't catch.
2
hart.sage2mo ago
Hold up though, what about checking the ground path first? I've seen a bad ground on a hot sensor give false readings that made people replace perfectly good parts.
5
emery_flores2mo ago
Buddy of mine replaced an alternator three times before finding a loose battery cable.
1