Negative deviation (RFC_12–15) means the injector is delivering less fuel than commanded. Positive deviation (rare) means over-fueling.
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For a complete list of specific electrical codes, you can reference the IVECO Stralis RFC Fault Codes Guide on Scribd or download the Iveco Stralis Fault Codes List PDF from TruckSpares365. Truckspares365 Do you have a specific DTC code iveco stralis rfc fault codes free
: Likely the rear control unit (Bosch box located behind the diesel tank) has failed or has a bad connection. How to Read Codes Without a Scanner iveco stralis rfc fault codes free