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.
1991 Ford Probe LX, AutomaticFACTORY OEM SERVICE PROCEDURE
3.0L PFI (Probe) Service Code Definitions
3.0L PFI (PROBE) SERVICE CODE DEFINITIONS
| Service Code | Test Condition(s) | Definition |
|---|---|---|
| 111 | KOEO/KOER/ CONTINUOUS | System Pass |
| 112 | KOEO/CONTINUOUS | ACT sensor circuit grounded. |
| 113 | KOEO/CONTINUOUS | ACT sensor circuit open. |
| 114 | KOEO/KOER | ACT sensor circuit is out of self-test range. |
| 116 | KOER | ECT sensor input is out of Self-Test range. |
| 117 | KOEO/CONTINUOUS | ECT circuit grounded |
| 118 | KOEO/CONTINUOUS | ECT circuit open |
| 121 | KOEO/KOER CONTINUOUS | TP sensor input is out of Self-Test range. |
| 122 | KOEO/CONTINUOUS | TP sensor input is less than Self-Test minimum voltage. |
| 123 | KOEO/CONTINUOUS | TP sensor input is greater than Self-Test maximum voltage. |
| 126 | KOEO/KOER/ CONTINUOUS | MAP sensor input is out of Self-Test range. |
| 129 | KOER | Insufficient MAF input change during Dynamic Response Test. |
| 144 | CONTINUOUS | No HEGO switching detected. |
| 167 | KOER | Insufficient TP input change during Dynamic Response Test. |
| 171 | CONTINUOUS | Lack of HEGO switching, system at adaptive limits (Rear Side). |
| 172 | KOER/CONTINUOUS | HEGO sensor circuit indicates system always lean (Rear Side). |
| 173 | KOER/CONTINUOUS | HEGO sensor circuit indicates system always rich (Rear Side). |
| 175 | CONTINUOUS | Lack of HEGO switching,fuel system at adaptive limits (Rear Side). |
| 176 | CONTINUOUS | HEGO sensor circuit indicates system always lean (Front Side). |
| 177 | CONTINUOUS | HEGO sensor circuit indicates system always rich (Front Side). |
| 179 | CONTINUOUS | Fuel system at part throttle lean adaptive limit, system rich (Rear Side). |
| 181 | CONTINUOUS | Fuel system at part throttle rich adaptive limit, system lean (Rear Side). |
| 182 | CONTINUOUS | Fuel system at idle lean adaptive limit, system rich (Rear Side). |
| 183 | CONTINUOUS | Fuel system at idle lean rich adaptive limit, system lean (Rear Side). |
| 188 | CONTINUOUS | Fuel system at part throttle lean adaptive limit, system rich (Front Side). |
| 189 | CONTINUOUS | Fuel system at part throttle rich adaptive limit, system lean (Front Side). |
| 191 | CONTINUOUS | Fuel system at idle lean adaptive limit, system rich (Front Side). |
| 192 | CONTINUOUS | Fuel system at idle rich adaptive limit, system lean (Front Side). |
| 211 | CONTINUOUS | Profile Ignition Pickup PIP) circuit failure. |
| 212 | CONTINUOUS | Loss of tachometer/IDM input to EEC processor. |
| 213 | KOER | EEC processor spark output (SPOUT) circuit open. |
| 326 | KOER/CONTINUOUS | PFE sensor circuit voltage lower than expected. |
| 327 | KOEO/KOER/ CONTINUOUS | PFE sensor circuit voltage below Self-Test minimum. |
| 332 | KOER/CONTINUOUS | Insufficient EGR flow detected. |
| 335 | KOEO | PFE sensor voltage out of Self-Test range. |
| 336 | KOER/CONTINUOUS | PFE sensor circuit higher than expected. |
| 337 | KOEO/KOER/ CONTINUOUS | PFE sensor voltage above Self-Test maximum. |
| 411 | KOER | Cannot control RPM during KOER low RPM check. |
| 412 | KOER | Cannot control RPM during KOER high RPM check. |
| 452 | CONTINUOUS | Insufficient input from the Vehicle Speed Sensor (VSS). |
| 511 | KOEO | ECC processor Read Only Memory (ROM) test failure. |
| 512 | CONTINUOUS | EEC processor Keep Alive Memory (KAM) test failure. |
| 513 | KOEO | Failure in EEC processor internal voltage. |
| 519 | KOEO | Power Steering Pressure Switch (PSPS) circuit open. |
| 521 | KOER | Power Steering Pressure Switch (PSPS) circuit did not change states. |
| 525 | KOEO | Vehicle was either in gear or AC was on during Self-Test. |
| 528 | CONTINUOUS | Clutch Engage switch circuit failure/not actuated during KOER. |
| 538 | KOER | Insufficient RPM change during KOER Dynamic Response Test. |
| 542 | KOEO/CONTINUOUS | Fuel pump circuit open, EEC processor to motor ground. |
| 543 | KOEO/CONTINUOUS | Fuel pump circuit open, battery to EEC processor. |
| 558 | KOEO | Electronic Vacuum Regulator (EVR) circuit failure. |
| 563 | KOEO | High Speed Electro Drive Fan HEDF) circuit failure. |
| 564 | KOEO | Electro Drive Fan (EDF) circuit failure. |
| 565 | KOEO | Canister purge circuit failure. |
| 998 | KOER | Hard fault present FMEM mode). |
| NO CODES | Unable to initiate Self-Test or unable to output Self-Test codes. | |
| CODES NOT LISTED | Service codes displayed are not applicable to vehicle being tested. | |
Factory Service Tools
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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.