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.
Symptom Diagnosis
Symptom checks cannot be used properly unless the problem occurs while the vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC TESTING and TESTS W/CODES articles in the ENGINE PERFORMANCE Section were performed before diagnosing a symptom.
Refer to DIAGNOSTIC ROUTINE INDEX CHART for a listing of the symptoms available for diagnosis. Go to the appropriate DIAGNOSTIC ROUTINE, as directed by the index chart based on symptoms, to diagnose problem.
| Title (Symptoms) | Routine Number |
|---|---|
| Cranks Normally But Won't Start | 201 |
| Cranks Normally But Won't Run (Stalls) | 202 |
| Cranks Normally But Slow To Start | 203 |
| Rough Idle | 204 |
| Misses Under Load | 205 |
| Low Idle (Stalls On Deceleration Or Quick Stop) | 206 |
| Hesitates Or Stalls On Acceleration | 207 |
| Backfire (Intake Or Exhaust) | 208 |
| Lack Of Power | 209 |
| Surges At Steady Speed | 210 |
| High Idle (Engine "Diesels") | 211 |
| Engine Noise | 212 |
| Poor Fuel Economy | 213 |
| High Oil Consumption | 214 |
| Spark Knock (Pings) | 215 |
| Engine Vibrates At Normal Speeds | 216 |
| Engine Runs Cold | 217 |
| Engine Runs Hot | 218 |
| Exhaust Smoke | 219 |
| Gas Smell | 220 |
| Check Engine Light Always On, Intermittently On or Never On | 221 |
| State Emission Test Failure | 222 |
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.