SPN 412 FMI 0 — EGR Temperature — Too High
What it means: EGR gas temperature is above the high limit.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Check coolant level and look for leaks — low coolant starves the EGR cooler.
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Oklahoma City, OK
Closest first. Tell them SPN 412 FMI 0 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Oklahoma City, OK · (405) 551-3320
- 0.0 mi away — based in Oklahoma City, OK · (405) 682-1362
- 0.0 mi away — based in Oklahoma City, OK · (405) 632-6010
What SPN 412 FMI 0 means
EGR gas temperature is above the high limit. Sustained high EGR temps point to an EGR cooler or coolant-flow problem and can damage the cooler/engine, so the ECM warns and derates.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Plugged or failing EGR cooler (reduced heat transfer)
- Low coolant level or poor coolant flow to the cooler
- Stuck-open EGR valve flowing too much hot gas
- Temperature sensor fault reading high (verify first)
First moves (roadside)
- Check coolant level and look for leaks — low coolant starves the EGR cooler.
- Watch EGR temp behavior under load to see if it's real or a sensor fault.
- Look for companion coolant-temp or EGR-position codes.
- Reduce load and get to a safe stop if temps keep climbing.
Common misdiagnoses
- Replacing the temp sensor when the EGR cooler was actually failing.
- Missing a low-coolant condition behind the high temps.
- Ignoring a stuck-open EGR valve as the heat source.
FAQ
EGR gas temperature is above the high limit. Sustained high EGR temps point to an EGR cooler or coolant-flow problem and can damage the cooler/engine, so the ECM warns and derates.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Plugged or failing EGR cooler (reduced heat transfer). Other possibilities include Low coolant level or poor coolant flow to the cooler; Stuck-open EGR valve flowing too much hot gas; Temperature sensor fault reading high (verify first).
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 412 FMI 0, or share the same subsystem.
- SCR Operator Inducement — Severe Derate Active (SPN 5246 FMI 0)
- Aftertreatment 1 Diesel Particulate Filter Differential Pressure - Data Valid But Above Normal Operating Range, Most Severe Level (DPF severely restricted / plugged) (SPN 3251 FMI 0)
- Aftertreatment 1 Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range, Most Severe Level (DEF quality/concentration incorrect) (SPN 4364 FMI 1)
- DPF Differential Pressure — Data Erratic (SPN 3251 FMI 2)
- DEF Dosing Unit — Not Responding Properly (SPN 3361 FMI 7)
- SCR Conversion Efficiency — Below Threshold (SPN 4364 FMI 18)
- DEF Quality — Out of Spec (SPN 4094 FMI 31)
- DEF Dosing Valve — Not Responding (SPN 5394 FMI 7)
Same symptom: Lost communication
Other datalink faults. A U-code is a network problem and is diagnosed at the datalink, not at the module that went quiet.
- Inlet (Upstream) NOx Sensor — Data Drifted (SPN 3216 FMI 20) · Aftertreatment & Emissions
- Engine Oil Pressure — Extremely Low (SPN 100 FMI 1) · Lubrication
- High Speed CAN Bus Fault (U0001) · Electrical, Charging & Network
- Lost Communication with ECM/PCM (U0100) · Electrical, Charging & Network
- Lost Communication with Fuel Injector Control Module (U0105) · Electrical, Charging & Network
- Battery / Charging Voltage — Low (SPN 168 FMI 18) · Electrical, Charging & Network
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.