This guide explains how to diagnose and resolve the SPN 27 FMI 4 fault code on an International MaxxForce 7 engine, which indicates an EGRP (Exhaust Gas Recirculation Position) signal out of range low.
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Understanding the EGR System
The Exhaust Gas Recirculation (EGR) valve is a key component of the EGR system, designed to reduce the formation of nitrogen oxides (NOx). It works by recirculating a portion of exhaust gases back into the intake air stream. Since these gases have already been combusted, they will not burn again, which lowers combustion temperatures and reduces NOx emissions.
Possible Causes of SPN 27 FMI 4 Fault
The fault occurs when the EGR position sensor signal is detected as being too low. Common causes include:
- EGRP signal circuit shorted to power
- EGRP signal circuit open or shorted to ground
- VREF (reference voltage) circuit open or shorted to ground
- Failed EGR valve assembly