JCB Fault Code
Free · no signupP0404
Limp Mode.
Variant 1
System
Not specified
Symptom
Limp Mode.
Diagnosis & fix steps
LOGIC: EGR Valve position is out of range.
ACTION: Remove EGR valve and check for carbon "coking." Use a diagnostic tool to perform a "Valve Sweep" test.
Red Seal field insights
Pro-Tip: JCBs are notorious for carbon buildup if they idle too much. If the valve is stuck, soak it in carb cleaner—don't pry on the butterfly or you'll snap the gear.
Variant 2
System
Emissions (EGR)
Symptom
Low Power / Black Smoke.
Diagnosis & fix steps
LOGIC: EGR Valve Position Error.
ACTION: Remove the EGR valve and check for carbon "coking." Perform a "Manual Reset" of the EGR adaptations via the JCB ServiceMaster tool.
Red Seal field insights
PRO-TIP: If the valve is physically stuck, don't force it. Soak the butterfly in carbon cleaner. If the internal gears are stripped, you will hear a "clicking" at key-on.
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