2631/1 Insufficient Air Flow

Enabling Conditions:

Engine coolant temp min.65*C(149*F)

Barometric Pressure  min.755

Ambient Temperature min.-8*C(18*F)

This code will provide a 25% derate

Verification: Once engine is at standard operating temp. road test unit at highway speeds. Coast for 30 seconds and then snap the throttle at 100% for min. 15 seconds.



  1. Any other faults present? If yes then troubleshoot those first
  2. Inspect air intake system for leaks or restrictions. Repair as necessary.
  3. Inspect wastegate actuator and plumbing going to and from actuator. Repair as necessary.
  4. Build unit air pressure up to 100psi, inspect air line connection to the wastegate solenoid. Repair any leaks.
  5. Compare intake manifold pressure to ambient pressure(Baro). If readings are not within 0.4 ambient pressure replace intake manifold pressure/temp sensor and inspect wiring.
  6. Connect using DDDL read EGR delta p voltage pin 109. If voltages are not within 0.55-0.83 volts, disconnect sensor and measure voltage across wiring. If voltages are within 0.55-0.83 volts replace EGR delta p sensor, if voltages are without of spec repair wiring.
  7. Inspect EGR delivery pipe delta p pressure ports for blockage, clean off any debris and road test to verify repair.
  8. Remove EGR hotpipe and inspect for debris or excessive amounts of soot, if debris/soot found replace EGR cooler and road test to verify repair.
  9. Connect using DDDL, under SCR voltage service routine read DOC inlet pressure(pint 87) and DPF outlet pressure(pin 72). If voltage is greater than 0.56volts replace suspect sensor, but if voltages are below 0.44volts repair wiring from sensor to ACM.
  10. Inspect DOC and DPF pressure sensor tubes for leaks or damages, Repair as necessary.
  11. Remove turbocharger inlet and outlet pipes and inspect for signs of oil or debris. Replace turbo is signs of oil or debris are present, then verify repair.

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