Truck Fault Codes

Detroit DD13 SPN 412 FMI 0 �?EGR Temperature Above Normal

SPN 412 FMI 0 on a Detroit DD13 means EGR outlet temperature is above the normal operating range. Connect DiagnosticLink to check the EGR bypass valve position and confirm it is not stuck open, monitor EGR temperature differential across the cooler, and inspect coolant flow to the cooler.

Code Details

Structured details for SPN 412 FMI 0
Display codeSPN 412 FMI 0
SPN412
FMI0
OEM codeNone listed
ManufacturerDetroit Diesel
SystemEngine �?EGR system
ComponentEGR cooler / EGR bypass valve / temperature sensor
Source addressUnknown or not applicable
Severitymedium
Review statussource backed
Source confidencemedium
Last reviewed2026-06-11

Plain-English Meaning

The DD13 EGR cooler reduces the temperature of recirculated exhaust gases before they enter the intake. When outlet temperature exceeds the normal threshold, the cooler is not cooling the EGR gases adequately. A stuck bypass valve routing hot gases around the cooler is the most common cause on the DD13 platform. On Freightliner Cascadia and Western Star trucks with the Detroit DD13, the EGR bypass valve is commanded by the MCM2.0. DiagnosticLink can command the bypass valve to specific positions and report actual valve position, making it straightforward to identify a stuck valve versus a temperature sensor fault. EGR cooler fouling from scale buildup — common in high-EGR operation on the DD13 under heavy load — reduces heat transfer performance and raises post-cooler EGR temperatures without any valve mechanical failure.

SPN 412 FMI 0 is EGR Temperature above normal. On Detroit DD13 MCM2.0, DiagnosticLink monitors EGR inlet and outlet temperatures, bypass valve position, and can command the bypass valve to test responsiveness. The EGR bypass valve on the DD13 is a known wear item that can stick from carbon buildup.

Common Symptoms

  • Check engine lamp active
  • Higher intake air temperatures from hot EGR contribution
  • Potential NOx increase affecting aftertreatment system loading
  • Higher than expected intake temperature — visible in DiagnosticLink live data
  • May accompany coolant loss if the EGR cooler has an internal leak

Possible Causes

Possible causes may include the items below. The list is not a parts diagnosis.

  • EGR bypass valve stuck in open or partially open position
  • Restricted coolant flow through the EGR cooler
  • EGR cooler core degradation
  • EGR temperature sensor fault
  • Internal scale fouling the EGR cooler passages from deferred coolant maintenance
  • EGR temperature sensor wiring fault

First Checks

  • Connect DiagnosticLink and check EGR bypass valve position and commanded state
  • Command the bypass valve open and closed to test responsiveness
  • Monitor EGR inlet vs. outlet temperature differential to quantify cooler heat rejection
  • Inspect for coolant loss that may indicate EGR cooler internal failure
  • Use DiagnosticLink to command the EGR bypass valve and confirm actual position tracks commanded position
  • Check coolant inhibitor levels and condition — low inhibitor causes scale that reduces EGR cooler performance

Can I Keep Driving?

Typically driveable. High EGR temperatures can elevate NOx output and accelerate aftertreatment loading.

SPN 3226 FMI 16Aftertreatment �?SCR system · Upstream NOx sensorSPN 110 FMI 0Engine �?cooling system · Engine coolant temperature sensor / cooling system

Related Lookup Pages

Sources

  • Detroit Diesel Service and Diagnostic Resources — Public Reference Detroit Diesel (Daimler Truck North America) · oem · accessed 2026-06-11 · confidence medium

    Source: Detroit Diesel (Daimler Truck North America), Detroit Diesel Service and Diagnostic Resources — Public Reference. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source
  • DiagnosticLink Detroit Diesel Corporation · oem · accessed 2026-05-05 · confidence medium

    Source: Detroit Diesel Corporation, DiagnosticLink. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source
  • SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium

    Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source

FAQ

Is the EGR bypass valve on the DD13 the same as on the DD15?

The DD13 and DD15 share a common EGR system architecture but are different displacement engines with different physical dimensions. The bypass valve design is similar, but specific part numbers differ. DiagnosticLink part look-up or the Detroit Diesel parts portal can confirm the correct valve for the specific engine.

Can the DD13 EGR bypass valve be cleaned in place to free it from carbon sticking?

In some cases, repeated DiagnosticLink bidirectional cycling of the valve combined with a solvent spray can free a mildly stuck bypass valve. For severely stuck valves, removal and manual cleaning or replacement is required. The valve is typically accessible without removing the entire EGR assembly.

Does a high EGR temperature on the DD13 always indicate the bypass valve is stuck?

Not always. If DiagnosticLink confirms the bypass valve is responding correctly to commands (opens and closes on demand), the high temperature is more likely from restricted coolant flow or a degraded cooler core. A temperature differential test across the cooler with the bypass confirmed closed quantifies the cooler's actual performance.