11 Jeep diagnostic codes on file. Each shows the symptom for free — unlock the full diagnosis, repair steps, and field insights with a free account.
| Code | System | Symptom | Fix |
|---|---|---|---|
| 11 | — | Engine cranks but won't start; Sudden stalling when hitting bumps; No spark. | Unlock |
| 12 | — | No driveability symptoms; Usually appears after battery work. | Unlock |
| 14 | — | Rough idle; Engine "running rich" (smell of unburned gas); Poor throttle response. | Unlock |
| 21 | — | Poor fuel economy; High idle; Engine stays in "Open Loop" mode. | Unlock |
| 24 | — | High idle; Transmission shifting issues (XJ Auto); Engine won't return to idle quickly. | Unlock |
| 27 | — | Misfire under load; Engine "stumbling" at highway speeds. | Unlock |
| 33 | — | No driveability symptoms unless A/C is in use. | Unlock |
| 42 | — | Engine won't start or dies immediately; No fuel pump prime sound. | Unlock |
| 51 | — | Lean misfire; Hissing sound; Hesitation on acceleration. | Unlock |
| 55 | — | No symptoms. | Unlock |
| B1239 | Climate Control (HVAC) | Air Trapped at Floor Vents | Unlock |
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