# 6420 John Deere won't rev over idle



## cooperthall (Aug 30, 2021)

Good Morning, I have a 6420 that was running fine and all of a sudden, the glow plug light in the dash started flashing and the tractor went to an idle. It won't increase speed with the throttle lever or the foot pedal. I switched the tractor off for about 10 minutes and restarted, no warning lights and ran fine for the rest of the day. Started it the next day and glow light is back on, flashing and tractor wont rev above idle again. The tractor has the 16 speed trans with power reverser. It does not have any sensors on the fuel filters. Has anyone experienced this problem? Thanks in advance, Coop.


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## BigT (Sep 15, 2014)

Good Morning Coop,

Your glow plug light has a dual function. When it is lights up with engine running, you have an error code stored in the engine control unit (ecu) computer. The best thing to do is to have your dealer technician connect his computer to your tractor and read the fault codes. If you know how to read the codes from the lcd display, you can do it yourself


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