Combined DOC / DPF / SCR Restriction and Efficiency Snapshot
Begin every complex aftertreatment diagnosis with a complete DOC–DPF–SCR data snapshot.
Fault Overview
System standard for capturing a single, comprehensive snapshot that includes DOC, DPF, and SCR temperatures, differential pressure, NOx values, dosing data, and soot/ash status for complex aftertreatment complaints. Incomplete data collection is the main reason complex aftertreatment jobs require multiple visits.
Engine & Platform Coverage
Symptoms
- •Aftertreatment full snapshot
- •DOC DPF SCR data capture
- •Comprehensive AT diagnosis
- •Restriction efficiency snapshot
Possible Causes
- 1.N/A — process standard. Used at the start of any complex restriction, regen, or efficiency diagnosis.
Wiring & Circuit Notes
Ensures all sensors are reporting before the snapshot is analyzed. Verify sensor integrity as part of the snapshot review.
DVOM Specs & Sensor Tests
Minimum snapshot content: engine speed/load/fuel rate; boost and EGR; DOC inlet/outlet temps; DPF inlet/outlet temps and DP; soot and ash load; SCR inlet/intermediate/outlet temps; upstream and downstream NOx with heater status; DEF level/quality/pressure/dosing quantity; active codes and inducement status.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Connect a Capable Scan Tool: Connect a capable scan tool. Ensure the tool can display all required PIDs simultaneously.
- 2Step 2 — Operate Under Complaint or Monitor Conditions: Operate under complaint or monitor conditions. Capture data under the conditions that produce the complaint.
- 3Step 3 — Capture the Full Snapshot: Capture the full snapshot including: engine speed, load, fuel rate; boost and EGR data; DOC inlet/outlet temps; DPF inlet/outlet temps and differential pressure; soot and ash load; SCR inlet/intermediate/outlet temps; upstream and downstream NOx with heater status; DEF level, quality, pressure, dosing quantity; active codes and inducement status.
- 4Step 4 — Analyze the Temperature Sequence, DP Behavior, NOx Conversion, and DEF Performance Together: Analyze the temperature sequence, DP behavior, NOx conversion, and DEF performance together. System-level analysis reveals interactions that single-subsystem diagnosis misses.
- 5Step 5 — Enter the Specific Diagnostic Path Indicated by the Snapshot: Enter the specific diagnostic path indicated by the snapshot (restriction, dosing, NOx, etc.).
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Directed by snapshot results.
Start Diagnosing This Fault Now
AI Diesel Tech walks you through every evidence gate in the correct order. Choose the plan that fits your shop.
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AI Diesel Tech — The Technician's Diagnostic Engine
AI Diesel Tech diagnostic logic is built by an ASE Certified Diesel Technician and engineered for professional shop use. Trusted by technicians nationwide — used in shops, fleets, and training programs.
Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.