2017 F250 6.2L Code P0300 Code
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Trailering
Joined: Jul 2022
Posts: 18
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2017 F250 6.2L Code P0300 Code
My wife is with our truck (and gooseneck horse trailer) about 1,000 miles from home in Ohio at a horse show. While driving down the road (without the trailer) the check engine light came on. The truck has about 50k miles on it. She called the local Ford dealership who said they couldn't look at the truck for about 3 weeks (she needs to come home in the next few days). So she took it to a local AutoZone so they could do a scan and see what the code was. It came back as a P0300 (Random Misfire Detected). When I called the local Ford dealership here at home, which has done all the service, all they told me was not to drive it.
As we know the 300 code can be a lot of things (spark plugs, ignition coil, catalytic converter, wiring harness, etc.). So she took it to a local mechanic who said he was getting misfire codes on all cylinders but after 3 hours of diagnostics, couldn't figure out what the issue was. I can't believe we're having this issue on a truck with only 50,000 miles on it. Before she just has to leave the truck at the local Ford dealership and fly home (and then fly back and drive the truck home when it's fixed in a few weeks), does anyone have any ideas? Or has anyone had this issue? Thanks.
As we know the 300 code can be a lot of things (spark plugs, ignition coil, catalytic converter, wiring harness, etc.). So she took it to a local mechanic who said he was getting misfire codes on all cylinders but after 3 hours of diagnostics, couldn't figure out what the issue was. I can't believe we're having this issue on a truck with only 50,000 miles on it. Before she just has to leave the truck at the local Ford dealership and fly home (and then fly back and drive the truck home when it's fixed in a few weeks), does anyone have any ideas? Or has anyone had this issue? Thanks.
Laughing Gas
Joined: Jan 2022
Posts: 779
Likes: 427
If you have a code scanner, swap a coil with the one next to it and see if the misfire code follows the coil. Or, do the same with spark plugs, swap cylinders and see if the code follows to the new cylinder. You can diagnose a bad coil or a plug like that. You can get a phone app like torque to read codes, but you need to buy a plug in OBD dongle.
Code 0300 just says there is a misfire, if a specific cylinder is obvious to the engine computer, it will specify which one, like P0306 is a misfire on cylinder #6.
Code 0300 just says there is a misfire, if a specific cylinder is obvious to the engine computer, it will specify which one, like P0306 is a misfire on cylinder #6.
Trailering
Joined: Nov 2019
Posts: 17
Likes: 4
So first thing I would Verify if Checked Engine Light "Flashed on and Off" of if just came on Steady. If a Cat Damage event can occur the PCM Flashes the Check Engine Light (To get Drivers Attention).I assume it's a intermittent Miss (not a dead skip). If Using a Scan Tool -- Monitor Cylinder Contribution or Power Balance Tests (Depending on Scan Tool they can be labeled differently) . If you still can't identify which cylinder is causing Misfire you need to view Mode 6 Data stored in PCM. Sometimes this is access is under Generic OBD Section. Scrolling through all the Info till you get to Misfire Information. Any Cylinder with a stored misfire value is where the problem exists. Most common concern is a Coil on Plug went Bad. As previous mentioned a Valve Spring is also possible - just not as common as a Coil on Plug. The challange with this Diag is finding someone who knows how to properly investigate the symptoms. The Dealer is Correct if a Truck/Car is Driven with a Misfire - that can damage a Catalytic Convertor. They get extremely unhappy if raw fuel go through them. Good Luck.
Fleet Mechanic
Joined: Jul 2008
Posts: 1,937
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From: Southern Crescent
The coil-on-plug design of the 6.2L is much the same as the Triton 5.4L and shares the same problems. After some miles (or years) moisture collects in or under the boot and corrosion sets in making bad connections to the spark plugs. I suspect that if the coil packs were removed and all the plug to coil and plug to wire to coil connections were cleaned of corrosion the problem would clear and she could drive the truck home.
The trick now is to figure out how to get that done with her there and you not.
The trick now is to figure out how to get that done with her there and you not.
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