ASE L2 case studies
ASE L2 · Put your knowledge to work in context.
ASE L2 - Electronic Diesel Engine Diagnosis Specialist is an advanced-level certification test in the ASE certification test series, administered by the National Institute for Automotive Service Excellence (ASE). It is aimed at experienced diesel technicians who already diagnose with scan tools, service information and lab scopes, and who want a credential that verifies their ability to troubleshoot electronically controlled diesel engines rather than to perform routine mechanical repair. The content spans general diesel engine diagnosis; diesel engine controls and electronic systems; air induction, turbocharger and exhaust systems; the diesel fuel system and injection; and emission control and aftertreatment. Because the test is advanced level, candidates are expected to reason from symptoms, data and circuit behavior instead of memorizing procedures. The ASE L2 case studies are 5 cases and about 3,126 words.
1Coolant Loss With Negative Cold Pressure Test
2013 class 8 tractor, 14.9 L, 612,000 miles. Driver reports the coolant level light on every few days; the shop tops off roughly 1 gallon per 500 miles.
638 words, about 3 min2Intermittent Pedal Correlation Derate After Pedal Replacement
2017 highway tractor, 12.8 L, 289,000 miles. Intermittent 25% derate, about once per 200 miles, always clears on key cycle.
632 words, about 3 min3Oil in the Charge Air Cooler - Turbo or Blowby?
2016 tractor, 14.9 L, 455,000 miles, uses 1 quart of oil every 350 miles. The CAC cold-side boot and the intake pipe behind the compressor are wet with oil.
634 words, about 3 min4Hot Hard Start, Low Rail Pressure, and Fuel in the Oil
2015 class 8 truck, 12.8 L common rail, 398,000 miles. Complaint: cranks 6–8 seconds before firing when hot, runs rough for 10 seconds, low power.
640 words, about 3 min5SCR Efficiency Code With Full DEF and Verified Pressure
2019 class 8 tractor, 15 L, 211,000 miles. Derate with an SCR efficiency code (NOx conversion below threshold).
582 words, about 3 min