Just realized my Snap-On scan tool was lying to me for months

Was chasing a misfire on a 2015 F-150 and the tool kept saying cylinder 3, swapped coils and plugs twice. Turned out the damn thing was misreading the crank sensor signal the whole time, anyone else had a tool feed them bad data like that?

3 comments

3 Comments

lewis.brian17h ago

Blew three hours on a Dodge last year because my scanner told me the coolant temp sensor was dead when it was really a loose ground strap under the battery tray. Makes you wonder if these tools are just elaborate pranks sometimes. Your story confirms I'm not the only one getting punked by expensive electronics.

laura_black17h ago

Gotta push back a little on this one man. I've been burned by bad diagnostics too, trust me, but the scanner didn't make you spend three hours on that Dodge, the wiring did. If you had a loose ground strap, that's a physical issue with the car's electrical system, not a flaw in the tool's logic. A scanner can only tell you what it sees through the wires, and if the ground path is flaky, the sensor readings are going to be garbage. It's like blaming your voltmeter for showing zero volts when the battery cable is off.

young.thomas13h ago

All due respect @laura_black, but a scanner that can't tell you the ground is bad is like a doctor who misses the obvious because they're too busy looking at the machine. The tool's supposed to put you on the right path, not send you on a three hour goose chase because it can't filter out garbage data.