Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Reference Value Symptom Chart
The Reference Value Symptom Chart provides guidance in selecting the appropriate parameter identification (PID) or measured signal related to the fault area. Select a symptom from the symptom chart along with the category number and go to the PID/Measured Signal Chart. For multiple symptoms, select the symptom that is the most evident.
| Symptom Occurs During | Symptom | Category Number |
|---|---|---|
| Startup: | No start/Normal crank | 1 |
| Hard start/Long crank | 2 | |
| Stall after start | 3 | |
| Diesels/Runs on | 4 | |
| Idle: | MIL | 5 |
| Stalls/Quits | 6 | |
| Slow | 7 | |
| Slow return | 8 | |
| Rolling | 9 | |
| Fast | 10 | |
| Rough | 11 | |
| Misses | 12 | |
| Backfires | 13 | |
| Acceleration: | Stalls/Quits | 6 |
| Misses | 12 | |
| Bucks/Jerks | 14 | |
| Backfires | 13 | |
| Hesitation | 15 | |
| Lack/Loss of power | 16 | |
| Surge | 17 | |
| Spark knock | 18 | |
| Cooling system temperature | 19 | |
| Poor fuel economy | 20 | |
| Emissions compliance | 21 | |
| Cruise: | Stalls/Quits | 6 |
| Misses | 12 | |
| Bucks/Jerks | 14 | |
| Backfires | 13 | |
| Lack/Loss of power | 16 | |
| Surge | 17 | |
| Spark knock | 18 | |
| Cooling system temperature | 19 | |
| Poor fuel economy | 20 | |
| Emissions compliance | 21 | |
| Deceleration: | Stalls/Quits | 6 |
| Backfires | 13 |
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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