Check out LMR's run-through of all the OBD1 codes for your Fox Body Mustang! This will help you diagnose your vehicle quickly and efficiently.
Often, when driving your Fox Body Mustang, so many different issues can come about at any time that can affect your vehicle's health. We at LMR have created this Fox Body Mustang OBD1 code guide and jumper procedure to better help you find and solve your specific problem without buying an expensive diagnostic code reader. Check out our guide below!
| Service Code | Service Code Definition | Service Code | Service Code Definition |
|---|---|---|---|
| 11 ORC | System PASS | 51 OC | ECT indicated -40°C (-40°F)/circuit open |
| 12 R | Cannot control rpm during Self-Test high rpm check | 53 OC | TP circuit above maximum voltage |
| 13 R | Cannot control rpm during Self-Test low rpm check | 54 OC | ACT indicated -40°C (-40°F)/circuit open |
| 14 C | PIP circuit failure | 56 OC | MAF circuit above maximum voltage (MA only) |
| 15 O | EEC processor Read Only Memory (ROM) test failed | 61 OC | ECT indicated 123°C (254°F)/circuit grounded |
| 15 C | EEC processor Keep Alive Memory (KAM) test failed | 63 OC | TP circuit below minimum voltage |
| 16 R | Rpm too low to perform EGO test | 64 OC | ACT indicated 123°C (254°F)/circuit grounded |
| 18 R | SPOUT circuit open | 66 C | MAF circuit below minimum voltage (MA only) |
| 18 C | IDM circuit failure/SPOUT circuit grounded | 67 O | Neutral Drive Switch (NDS) circuit open - A/C ON during Self-Test |
| 19 O | Failure in EEC processor internal voltage | 74 R | Brake On/Off (BOO) circuit open/not actuated during Self-Test |
| 21 OR | ECT out of Self-Test Range | 75 R | Brake On/Off (BOO) circuit closed/EEC processor input open |
| 22 ORC | MAP/BP out of Self-Test range | 77 R | Brief WOT not sensed during Self-Test/Operator error |
| 23 OR | TP out of Self-Test range | 79 O | A/C on/Defrost on during Self-Test |
| 24 OR | ACT out of Self-Test range | 81 O | Air Management 2 (AM2) circuit failure |
| 26 OR | MAF out of Self-Test range (MA only) | 82 O | Air Management 1 (AM1) circuit failure |
| 29 C | Insufficient input from the Vehicle Speed Sensor (VSS) | 84 O | EGR Vacuum Regulator (EVR) circuit failure |
| 31 ORC | EVP circuit below minimum voltage | 85 O | Canister Purge (CANP) circuit failure |
| 32 ORC | EVP voltage below closed limit | 87 OC | Fuel pump primary circuit failure |
| 33 RC | EGR valve opening not detected | 91 R | HEGO sensor circuit indicates system lean (left HEGO) |
| 34 ORC | EVP voltage above closed limit | 91 C | No HEGO switching detected (left HEGO) |
| 35 ORC | EVP circuit above maximum voltage | 92 R | HEGO sensor circuit indicates system rich (left HEGO) |
| 41 R | HEGO sensor circuit indicates system lean (right HEGO) | 94 R | Thermactor air system inoperative (left side) |
| 41 C | No HEGO switch detected (right HEGO) | 95 OC | Fuel pump secondary circuit failure |
| 42 R | HEGO sensor circuit indicates system rich (right HEGO) | 96 OC | Fuel pump secondary circuit failure |
| 44 R | Thermactor air system inoperative (right side) | 98 R | Hard fault is present - FMEM mode |
| 45 R | Thermactor air upstream during Self-Test | NO CODES | Unable to initiate Self-Test or unable to output Self-Test codes |
| 46 R | Thermactor air not bypassed during Self-Test | CODES NOT LISTED | Service codes displayed are not applicable to the vehicle being tested |
Often on your Mustang, codes can be present even if the check engine light hasn't been activated, so LMR has put together a list of steps a cheap and easy way to dump the computer codes without using expensive equipment. Also, please be aware that trouble codes are 2 or 3 digits. No cars use both digits, so be aware of that during your diagnosis.
That's it! Dumping your codes can be quick and easy if provided with the correct steps. As always, for all things engine-related for your Fox Body Mustang, check out all of our products at Late Model Restoration.
