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.
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HOMESERVICE MANUALSMERCURY1991COUGAR LS, 3.8 4REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 3.8LKOEO CODE/TEST MENU - 3.8L
1991 Mercury Cougar LS, 3.8 4
KOEO Code/Test Menu - 3.8L
1991 Mercury Cougar LS, 3.8 4SECTION KOEO Code/Test Menu - 3.8L
KOEO SELF-TEST - CIRCUIT TEST & STEP MENU
| Code No. | Go To: Test No. (Step No.) | |
|---|---|---|
| 112 | DA (20) | |
| 113 | DA (10) | |
| 114 | DA (1) | |
| 116 | DA (1) | |
| 117 | DA (20) | |
| 118 | DA (10) | |
| 121 | DH (2) | |
| 122 | DH (10) | |
| 123 | DH (3) | |
| 126 (All Except SPFI-MA AXODE) | DF (1) | |
| 158 | DC (20) | |
| 159 | DC (1) | |
| 327 | DL (1) | |
| 335 | DL (8) | |
| 337 | DL (5) | |
| 341 (SPFI-MA SC Only) | KP (1) | |
| 511 | QB (3) | |
| 513 | Replace ECA unit | |
| 519 (SPFI-MA AXODE Only) | FF (1) | |
| 522 | T (80) | |
| 525 (All Except SPFI-MA AXODE) | TA (1) | |
| 526 (All Except SPFI-MA AXODE) | FD (1) | |
| 539 | KM (40) | |
| 542 | X (90) | |
| 543 | X (100) | |
| 556 | ||
| SPFI-MA AXODE | X (15) | |
| SPFI-MA RWD & SPFI-MA SC | J (7) | |
| 558 | DL (11) | |
| 563 (SPFI-MA AXODE & SPFI-MA SC Only) | X (30) | |
| 564 (SPFI-MA AXODE & SPFI-MA SC Only) | X (80) | |
| 565 | KD (6) | |
| 621 (SPFI-MA AXODE Only) | T (10) | |
| 622 (SPFI-MA AXODE Only) | T (10) | |
| 624 (SPFI-MA AXODE Only) | T (10) | |
| 625 (SPFI-MA AXODE Only) | T (10) | |
| 629 (SPFI-MA AXODE Only) | TB (1) | |
| 636 (SPFI-MA AXODE Only) | T (10) | |
| 637 (SPFI-MA AXODE Only) | T (10) | |
| 638 (SPFI-MA AXODE Only) | T (10) | |
| 641 (SPFI-MA AXODE Only) | T (10) | |
| 652 (SPFI-MA AXODE Only) | T (10) | |
| No Codes/Codes Not Listed | QA (1) | |
RENDER: 1.0x
NO RELATED
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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.