Common Alert Codes

Dale's APU Sales

Diesel Particulate Filter (DPF) Alert Codes


P2002: DPF Efficiency Below Threshold


Symptoms:

  • Reduced engine performance
  • Increased fuel consumption
  • DPF warning light illuminated
  • Possible black smoke from the exhaust


Possible Causes: 

  • Clogged DPF requiring cleaning or replacement
  • Faulty differential pressure sensor
  • Exhaust leaks before the DPF
  • Engine performance issues are causing excessive soot production
  • Damaged DPF substrate


Recommended Action:

  • Perform a diagnostic scan to confirm the code and check the freezing frame data
  • Inspect DPF condition and measure back pressure
  • Check for exhaust leaks
  • Verify proper engine operation
  • Professional DPF cleaning or replacement may be required


P2459: DPF Regeneration Too Frequent


Symptoms:

  • Excessive fuel consumption
  • Frequent high-temperature warnings
  • Reduced efficiency
  • More frequent idle periods for regeneration


Possible Causes: 

  • Engine issues causing excessive soot production (injectors, turbo)
  • Faulty temperature or pressure sensors
  • Failed DOC reducing regeneration effectiveness
  • Partially clogged DPF
  • EGR system issues


Recommended Action:

  • Comprehensive engine diagnostics
  • Check sensor operation
  • Inspect the DOC condition
  • Evaluate DPF condition and consider cleaning
  • Review driving patterns (short trips can contribute to this issue)


P244A: DPF Differential Pressure Too High


Symptoms:

  • Engine power reduction
  • A regeneration cycle that doesn't complete
  • The engine may enter limp mode
  • Excessive exhaust back pressure


Possible Causes: 

  • Severely clogged DPF
  • Restricted exhaust system
  • A faulty pressure sensor or wiring
  • Failed regeneration system
  • Physical damage to DPF


Recommended Action:

  • Immediate attention is required to prevent DPF damage
  • Diagnostic scan and pressure testing
  • Possible DPF cleaning or replacement
  • Check the exhaust system for other restrictions


P2463: DPF Soot Accumulation


Symptoms:

  • DPF warning light
  • Request for parked regeneration
  • Reduced performance
  • Increased fuel consumption


Possible Causes: 

  • Normal soot accumulation requiring regeneration
  • Failed previous regeneration attempts
  • Driving conditions are not conducive to passive regeneration
  • Engine issues creating excessive soot 


Recommended Action:

  • Attempt active regeneration if the vehicle is equipped with this feature
  • Drive at highway speeds for 20-30 minutes if possible
  • If regeneration fails, a professional diagnosis is required
  • May require forced regeneration using diagnostic equipment

Selective Catalytic Reduction (SCR) Alert Codes 


P207F: Reductant Quality Performance 


Symptoms:

  • DEF warning light
  • Potential power limitation
  • SCR system efficiency warnings
  • Increased NOx emissions 


Possible Causes: 

  • Contaminated or poor-quality DEF
  • DEF that has exceeded its shelf life
  • Faulty DEF quality sensor
  • Crystallized DEF in the system
  • Water contamination in the DEF tank


Recommended Action:

  • Drain and replace DEF with fresh, high-quality fluid
  • Diagnostic scan to check sensor operation
  • Possible DEF system cleaning if crystallization has occurred
  • Reset adaptation values after repair 


P208E: DEF Injector Circuit Malfunction 


Symptoms:

  • SCR system performance warnings
  • Possible power reduction
  • DEF is not being consumed
  • The smell of ammonia may be absent from the exhaust 


Possible Causes: 

  • Clogged DEF injector
  • Electrical issues with the injector circuit
  • Crystallized DEF in the injector
  • Injector heater failure
  • Wiring harness damage


Recommended Action:

  • Diagnostic scan to check circuit integrity
  • Injector inspection and cleaning, or replacement
  • Check for corrosion at electrical connections
  • Verify proper DEF pump operation 


P20EE: NOx Catalyst Efficiency Below Threshold 


Symptoms:

  • Check engine light
  • Potentially, no other immediate symptoms
  • Eventually, it may trigger emissions system limitations


Possible Causes: 

  • Aging or damaged SCR catalyst
  • DEF delivery issues
  • Exhaust leaks
  • Faulty NOx sensors
  • Hydrocarbon contamination of the catalyst


Recommended Action:

  • Comprehensive SCR system diagnostics
  • NOx sensor testing
  • Exhaust system inspection for leaks
  • Possible catalyst replacement
  • Check for engine issues causing excessive hydrocarbons


P204F: Reductant System Performance / No Injection 


Symptoms:

  • DEF warning indicators
  • Reduced engine performance
  • DEF is not being consumed
  • Increased NOx emissions


Possible Causes: 

  • DEF pump failure
  • Blocked DEF lines
  • Frozen DEF in cold weather
  • Air in the DEF system
  • DEF injector failure 


Recommended Action:

  • Check DEF pump operation and pressure
  • Inspect DEF lines for blockage
  • Verify DEF injector operation
  • Check DEF heater function in cold weather
  • May require DEF system priming

Diesel Oxidation Catalyst (DOC) & EGR Alert Codes 


P0401: EGR Flow Insufficient 


Symptoms:

  • Reduced power
  • Poor fuel economy
  • Black smoke
  • Rough idle
  • Increased NOx emission


Possible Causes: 

  • Clogged EGR valve or cooler
  • EGR valve stuck closed
  • Faulty EGR control solenoid
  • Carbon buildup in the intake manifold
  • Damaged EGR gaskets are causing leaks


Recommended Action:

  • EGR system inspection and cleaning
  • EGR valve function testing
  • Check for intake leaks
  • Possible component replacement
  • Verify proper engine control module operation


P0420: Catalyst System Efficiency Below Threshold 


Symptoms:

  • Check engine light
  • Potentially, no other immediate symptoms
  • Possibly increased emissions
  • Failed emissions test


Possible Causes: 

  • Aging or damaged DOC
  • Exhaust leaks
  • Engine running in rich condition
  • Oil or coolant contamination in the exhaust
  • Faulty oxygen sensors


Recommended Action:

  • Exhaust system inspection
  • Check for exhaust leaks
  • Verify oxygen sensor operation
  • Engine performance diagnosis
  • Possible DOC replacement


P0299: Turbocharger Under Boost Condition 


Symptoms:

  • Significant power loss
  • Black smoke
  • Delayed acceleration
  • Turbo lag
  • Poor fuel economy


Possible Causes: 

  • Clogged air filter
  • Exhaust restrictions, including a clogged DPF
  • Turbocharger mechanical issues
  • Boost pressure sensor failure
  • Air leaks intake
  • Wastegate issues


Recommended Action:

  • Complete intake and exhaust system inspection
  • Turbocharger evaluation
  • Check for boost leaks
  • Measure actual boost pressure
  • Verify wastegate operation

How to Respond to Alert Codes 


Immediate Actions


When you see a warning light or alert code related to your emissions system:

  1. Note Any Performance Changes: Document any changes in engine performance, fuel consumption, or unusual sounds/smells to help with diagnosis.
  2. Check for Multiple Codes: Multiple related codes can help pinpoint the exact issue. Make a note of all codes present.
  3. Consider Recent Operating Conditions: Have you been making short trips? Using a different fuel? Operating in extreme temperatures? This information helps with diagnosis.
  4. Avoid Extreme Measures: Don't continue to operate the vehicle with severe warning lights. This can cause additional damage.
  5. Contact a Specialist: Emissions systems are complex and interconnected. Professional diagnosis ensures the root cause is identified and properly addressed.


Preventative Maintenance 


To reduce the likelihood of emissions system failures: 

  1. Regular DPF Cleaning: Schedule professional DPF cleaning at recommended intervals.
  2. Quality Fuel and DEF: Use high-quality diesel fuel and DEF from reputable sources.
  3. Driving Patterns: When possible, include periods of highway driving to facilitate passive regeneration.
  4. Engine Maintenance: Keep up with regular engine maintenance, as engine issues often lead to emissions system problems.
  5. Telematics Monitoring: Consider our telematics monitoring service for early detection of potential issues. 

Dale's APU Sales Emissions Services (Call Outs Section) 


At Dale's APU Sales, we offer comprehensive emissions system services:

  1. Professional DPF Cleaning: Our state-of-the-art cleaning system restores DPF function without damaging the filter.
  2. Emissions Diagnostics: Advanced diagnostic equipment to accurately identify the root cause of emissions issues.
  3. DOC & SCR Repair: Expert repair and replacement of all emissions system components.
  4. DPF Exchange Program: Get back on the road quickly with our exchange program.
  5. Preventative Maintenance: Regular inspections and cleaning to prevent costly failures.
  6. Telematics Monitoring: Real-time monitoring of your emissions system to catch issues before they cause breakdowns.


Contact us today to schedule your emissions system service or to learn more about how we can help keep your truck running efficiently and in compliance with emissions regulations.