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Detroit Diesel SPN 3242 FMI 16 indicates that the temperature at the DPF inlet has exceeded the acceptable operating threshold. This code appears on DD13, DD15, and DD16 engines and like the outlet temperature fault is a serious condition that can damage the DPF substrate and exhaust components. The inlet sensor is located before the DPF and high readings here often point to combustion or regen system issues upstream of the filter.
Symptoms
- Check engine light on
- DPF warning light illuminated Active engine derate condition
- Excessive exhaust temperatures
- Possible burning smell from exhaust system
- Regeneration may be active or stuck
- May appear alongside DPF outlet temperature codes
Cause
This code triggers when the DPF inlet temperature sensor detects temperatures above the maximum threshold before the exhaust enters the filter. Common causes include:
- Engine running excessively rich causing high exhaust temperatures
- Uncontrolled regeneration or over fueling during regen cycle
- Faulty HC dosing injector delivering too much fuel
- Turbocharger issues affecting exhaust temperature management
- Failed DPF inlet temperature sensor giving false readings
- Exhaust brake or restriction causing heat buildup
- Faulty regen control system unable to regulate inlet temperatures
Can You Keep Driving?
No. High DPF inlet temperatures can rapidly damage the filter substrate and exhaust components. Stop the vehicle safely away from flammable materials and allow the exhaust system to cool before any further diagnosis or operation.
Recommended Action
Stop the vehicle and allow the exhaust to cool completely. Do not initiate a regeneration with this fault active. Have the HC dosing injector, engine fueling system, turbocharger, and regen control system inspected by a qualified diesel technician. Check for signs of DPF substrate damage before returning to service.
It means the temperature entering the DPF has exceeded the maximum acceptable threshold, indicating a serious condition upstream of the filter that requires immediate attention.
The most common causes are engine over fueling, an uncontrolled regeneration, a faulty HC dosing injector, turbocharger issues, or a failed DPF inlet temperature sensor.
No. Continued operation with high DPF inlet temperatures risks permanent damage to the filter and exhaust system components. Stop safely and allow the system to cool.
Yes. The ECM will trigger an immediate derate to protect the DPF and exhaust system from damage caused by excessive inlet temperatures.
The root cause must be diagnosed and repaired. Have the HC dosing injector, engine fueling, and regen control system inspected. Do not attempt regeneration until the cause of the high inlet temperature has been identified and resolved.
Related codes
Need Immediate Help With This Fault Code?
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Important Notice
The information provided above is for general informational purposes only and should not replace official OEM service procedures. Always consult the manufacturer’s service manual or a qualified diesel technician before performing repairs. Operating a vehicle with active fault codes may result in further damage.