The EEC-IV equipped engines use an older diagnostic system to monitor and report engine related malfunctions. This system is known as On Board Diagnostics (OBD-I). The Diagnostic Trouble Codes (DTC’s) are two or three digit numbers and can be read through the use of a scan tool, an analog voltmeter, or with the Malfunction Indicator Light (MIL) [Check Engine or Service Engine Soon light].
Steps on how to test the EEC-IV / OBD-I vehicles can be found here at: Testing EEC-IV Equipped Engines
This page contains the 2-digits codes that you will get as a result of that test.
Differences in test mode noted as:
(O) = Key On Engine Off test
(R) = Key On Engine Running test
(M) = Memory code
| Code | Definitions |
|---|---|
| 111 | System checks OK |
| 112 | (O,M) Intake Air Temperature (IAT) sensor is/was low or grounded – IAT |
| 113 | (O,M) IAT sensor is/was high or open – IAT |
| 114 | (O,R) IAT sensor out of range – IAT |
| 116 | (O,R) Engine Coolant (ECT) sensor out of range – ECT |
| 117 | (O,M) ECT sensor is/was low or grounded – ECT |
| 118 | (O,M) ECT sensor is/was high or open – ECT |
| 121 | (O,R,M) Throttle Position (TP) sensor out of range – TPS |
| 122 | (O,M) TP low (possibly grounded or open circuit) – TPS |
| 123 | (O,M) TP is/was high or short to power – TPS |
| 124 | (M) TP voltage was higher than expected – Fuel control |
| 125 | (M) TP voltage was lower than expected – Fuel control |
| 126 | (O,R,M) MAP or BARO sensor out of range – “>MAP |
| 128 | (M) MAP vacuum has not been changing – check vacuum lines – “>MAP |
| 129 | (R) No MAP or Mass Air Flow sensor change during “goose” test – MAP MAF |
| 136 | (R) Oxygen sensor not switching/system lean Left or Front HO2S – Fuel control |
| 137 | (R) Oxygen sensor not switching/system rich Left or Front HO2S – Fuel control |
| 138 | (R) Fault in Cold Start Injector circuit – Fuel control |
| 139 | (M) Oxygen sensor not switching Left or Front HO2S – Fuel control |
| 144 | (M) Oxygen sensor not switching Single, Right or Rear HO2S – Fuel control |
| 157 | (R,M) Mass Air Flow signal is/was low or grounded – MAF |
| 158 | (O,R,M) MAF sensor is/was high or short to power – MAF |
| 159 | (O,R) MAF sensor is/was out of range – MAF |
| 167 | (R) No Throttle Position sensor change in “goose” test (must get at least 25% rotation) – TPS |
| 171 | (M) Oxygen sensor not switching – system was at adaptive limits – Single, Right or Rear HO2S – Fuel control |
| 172 | (R,M) Oxygen sensor not switching – system is or was lean – Single, Right or Rear HO2S – Fuel control |
| 173 | (R,M) Oxygen sensor not switching – system is or was rich – Single, Right or Rear HO2S – Fuel control |
| 174 | (M) Oxygen sensor was slow in switching Single, Right or Rear HO2S – Fuel control |
| 175 | (M) Oxygen sensor not switching – system was at adaptive limits – Left or Front HO2S – Fuel control |
| 176 | (M) Oxygen sensor not switching – system is or was lean Left or Front HO2S – Fuel control |
| 177 | (M) Oxygen sensor not switching – system was rich Left or Front HO2S – Fuel control |
| 178 | (M) Oxygen sensor was slow in switching Left or Front HO2S – Fuel control |
| 179 | (M) Fuel system was rich at part throttle Single, Right or Rear HO2S – Fuel control |
| 181 | (M) Fuel system was lean at part throttle Single, Right or Rear HO2S – Fuel control |
| 182 | (M) Fuel system was rich at idle Single, Right or Rear HO2S – Fuel control |
| 183 | (M) Fuel system was lean at idle Single, Right or Rear HO2S – Fuel control |
| 184 | (M) Mass Air (MAF) output higher than expected – Fuel control |
| 185 | (M) Mass Air (MAF) output lower than expected – Fuel control |
| 186 | (M) Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected – Fuel control |
| 187 | Injector pulse width shorter than expected or Mass Air Flow (MAF) higher than expected – Fuel control |
| 188 | (M) Fuel system was rich at part throttle – Left or Front HO2S – Fuel control |
| 189 | (M) Fuel system was lean at part throttle – Left or Front HO2S – Fuel control |
| 191 | (M) Fuel system was rich at idle – Left or Front HO2S – Fuel control |
| 192 | (M) Fuel system was lean at idle – Left or Front HO2S – Fuel control |
| 193 | Failure in Flexible Fuel (FF) sensor circuit – Fuel control |
| 194 | (M) Perform cylinder balance test to check for inoperative injectors |
| 195 | (M) Perform cylinder balance test to check for inoperative injectors |
| 211 | (M) Ignition PIP signal was erratic or missing – Ignition Systems |
| 212 | (M) Ignition TACH signal was erratic (module/wiring) or SPOUT circuit fault – Ignition Systems |
| 213 | (R) Ignition SPOUT or SAW circuit open or shorted – Ignition Systems |
| 214 | (M) Error in Cylinder ID (CID) circuit or signal – Ignition Systems |
| 215 | (M) Primary circuit failure – ignition coil 1 – Ignition Systems |
| 216 | (M) Primary circuit failure – ignition coil 2 – Ignition Systems |
| 217 | (M) Primary circuit failure – ignition coil 3 – Ignition Systems |
| 218 | (M) IDM signal open or high or left coil pack failure – Ignition Systems |
| 219 | (M) SPOUT circuit failure, timing defaulted to 10 degrees – follow code 213 diagnosis |
| 222 | (M) IDM open or high or right coil pack failure – Ignition Systems |
| 223 | (M) Dual Plug (DPI), SPOUT or IDM circuit fault – Ignition Systems |
| 224 | (M) Failure in ignition coil primary circuit – Ignition Systems |
| 225 | (R) Knock sensor not tested (ignore if not pinging) – KS |
| 226 | (O) Ignition Diagnostic Monitor (IDM) signal fault – Ignition Systems |
| 232 | (M) EI primary coil circuit failure – Ignition Systems |
| 238 | (M) EI primary circuit failure – ignition coil 4 – Ignition Systems |
| 311 | (R) AIR system not working – Single, Right or Rear HO2S – Air Injection |
| 312 | (R) AIR not diverting – Air Injection |
| 313 | (R) AIR not bypassing – Air Injection |
| 314 | (R) AIR inoperative, Left or Front HO2S – Air Injection |
| 326 | (R,M) Pressure Feedback EGR shows low pressure EGR not seating or not seating intermittently – PFE |
| 327 | (O,R,M) EGR feedback signal is/was low – EVR or PFE |
| 328 | (O,R,M) EGR Valve Position (EVP) is/was low – EVR |
| 332 | (R,M) EGR did not open/respond during test or if memory code, did not open intermittantly – EVR or PFE |
| 334 | (O,R,M) EVP sensor is/was high – EVR |
| 335 | (O) EGR feedback signal is/was out of range – EVR or PFE |
| 336 | (O,R,M) PFE sensor signal is/was was high – “>PFE |
| 337 | (O,R,M) EGR feedback signal is/was was high – EVR |
| 338 | (M) Cooling system did not heat up (check cooling system / thermostat operation) |
| 339 | (M) Cooling system overheated (check cooling system / thermostat operation) |
| 341 | (O) Octane jumper installed (information only code to notify you if it is installed) |
| 411 | (R) Idle speed system not controlling idle properly (generally idle too high) – ISC |
| 412 | (R) Idle speed system not controlling idle properly (generally idle too low) – ISC |
| 452 | (M) Vehicle Speed Sensor (VSS) problem |
| 511 | (O) No power to PCM pin 1 or bad PCM (processor) |
| 512 | (M) Memory power (PCM pin 1) was interrupted – Was battery disconnected ? |
| 513 | (O) Replace processor (PCM) (internal failure) |
| 519 | (O) PSP switch/circuit open – PSP |
| 521 | (R) Wheel not turned during test or PSP problem – PSP |
| 522 | (O) Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault – PNP |
| transmission MLP sensor out of range in park – Transmissions | |
| 524 | Problem in low speed fuel pump circuit – Power / Fuel Pump Circuits |
| 525 | (O,M) Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault – PNP |
| 528 | (M) System shows voltage at pin 10 (is A/C on ?) or pin 30 (PNP, CPP switch) – PNP |
| 529 | (M) Data Communications Link to processor failure |
| Service any EEC codes, erase memory and retest. If code is still present refer to instrument cluster diagnosis manual. | |
| 533 | (M) Data Communications Link to instrument cluster failure – see 529 |
| 536 | (O,R,M) Brake On Off open or shorted to ground – BOO |
| 538 | (R) System did not receive “goose” test – TESTS |
| 539 | (O) System shows voltage at PCM pin 10. Is A/C on ? |
| 542 | (O,M) Fuel pump open, bad ground or always on – – Power / Fuel Pump Circuits |
| 543 | (O) Fuel pump monitor circuit shows no power – Power / Fuel Pump Circuits |
| (M) (Service 556 code first if present) Fuel pump relay or battery power feed was open – Power / Fuel Pump Circuits | |
| 551 | Problem in Intake Manifold Runner Control (IMRC) solenoid/circuit – Solenoids |
| 552 | (O) AIRB solenoid/circuit failure – Solenoids |
| 553 | (O) AIRD solenoid/circuit failure – Solenoids |
| 554 | (O) Fuel Press Regulator Control solenoid/circuit fault – Power / Fuel Pump Circuits |
| 556 | (O,M) Fuel pump relay primary circuit fault – Power / Fuel Pump Circuits |
| 557 | (O,M) Low speed pump relay primary circuit fault – Power / Fuel Pump Circuits |
| 558 | (O) EGR vacuum regulator solenoid/circuit failure – EVR or PFE or Solenoids |
| 559 | (O) A/C relay primary circuit fault – A/C and Fan Circuits |
| 563 | (O) High Fan Control (HFC) circuit failure – A/C and Fan Circuits |
| 564 | (O) Fan Control (FC) circuit failure – A/C and Fan Circuits |
| 565 | (O) Canister Purge 1 solenoid/circuit failure – Solenoids |
| 566 | (O) transmission 3/4 shift solenoid/circuit – Transmissions |
| 569 | (O) Canister Purge 2 solenoid/circuit failure – Solenoids |
| 578 | (M) A/C pressure sensor VREF short to ground – A/C and Fan Circuits |
| 579 | (M) ACP sensor did not change with A/C on – A/C and Fan Circuits |
| 581 | (M) Cooling fan current was excessive – A/C and Fan Circuits |
| 582 | (O) Open cooling fan circuit – A/C and Fan Circuits |
| 583 | (M) Fuel pump current was excessive – Power / Fuel Pump Circuits |
| 584 | (M) Open power ground circuit – Power / Fuel Pump Circuits |
| 585 | (M) A/C clutch current was excessive – A/C and Fan Circuits |
| 586 | (M) Open circuit in A/C clutch – A/C and Fan Circuits |
| 587 | (O, M) Communication problem between PCM and Variable Control Relay Module (VCRM) – Power / Fuel Pump Circuits |
| 617 | (M) Transmission shift failure (1/2 shift) – Transmissions |
| 618 | (M) Transmission shift failure (2/3 shift) – Transmissions |
| 619 | (M) Transmission shift failure (3/4 shift) – Transmissions |
| 621 | (O) Solenoid/circuit failure – shift solenoid 1 – Transmissions |
| 622 | (O) Solenoid/circuit failure – shift solenoid 2 – Transmissions |
| 624 | (O,M) Solenoid/circuit failure -Electronic Pressure Control (EPC) current is high – Transmissions |
| 625 | (O,M) Solenoid/circuit failure – Electronic Pressure Control (EPC) current is low – Transmissions |
| 626 | (O) Transmission Coast Clutch (CCS) Solenoid/circuit fault – Transmissions |
| 627 | (O) Torque Converter Clutch circuit fault – Transmissions |
| 628 | (M) Excessive converter clutch slippage – Transmissions |
| 629 | (O,M) Torque Converter Clutch circuit fault – Transmissions |
| 631 | (O) Overdrive Cancel Light circuit problem – Transmissions |
| 632 | (R) E4OD – Transmission Control Switch (TCS) should be cycled once between engine ID and Goose test |
| 633 | (O) 4x4L switch should be in 4×2 or 4×4 high for the test |
| 634 | (O,M) Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault |
| Electronic shift transmission – Manual Lever Position (MLP) sensor out of range in PARK – Transmissions | |
| 636 | (O,R) Transmission Oil Temperature (TOT) sensor out of range – Transmissions |
| 637 | (O,M) TOT sensor is/was high or open – Transmissions |
| 638 | (O,M) TOT sensor is/was low or grounded – Transmissions |
| 639 | (R,M) Transmission Speed sensor (TSS) circuit fault – Transmissions |
| 641 | (O) Transmission solenoid/circuit failure Shift Solenoid 3 – Transmissions |
| 643 | (O)(M) Torque Converter Clutch (TCC) circuit – Transmissions |
| 645 | (M) Transmission 1st gear failure – Transmissions |
| 646 | (M) Transmission 2nd gear failure – Transmissions |
| 647 | (M) Transmission 3rd gear failure – Transmissions |
| 648 | (M) Transmission 4th gear failure – Transmissions |
| 649 | (M) Transmission EPC system failure – Transmissions |
| 651 | (M) Transmission EPC solenoid/circuit fault – Transmissions |
| 652 | (O) Torque Converter Clutch (TCC) circuit fault – Transmissions |
| 654 | (O) Transmission selector not in PARK – Transmissions |
| 656 | (M) Torque Converter Clutch (TCC) slip – Transmissions |
| 657 | (M) Transmission temperature was excessive – Transmissions |
| 998 | (R) Did not pass Key On Engine Off test yet (Get 111 in KOEO first) |
| (O) Transmission Electronic Pressure Control (EPC) solenoid/circuit fault – Transmissions | |
| Code | Definitions: |
| ACT | Air Charge Temperature Sensor |
| BP | See MAP |
| EEC | Electronic Engine Control System |
| ECT | Engine Coolant Temperature Sensor |
| EGR | Exhaust Gas Recirculation Valve |
| EVP | EGR Valve Position Sensor |
| HEGO | Heated Exhaust Gas Oxygen Sensor |
| KOEO | Key On Engine Off |
| KOER | Key On Engine Running |
| MAF | Mass Air Flow Sensor |
| MAP | Manifold Absolute Pressure Sensor |
| MLP | Manual Lever Position |
| PCM | Powertrain Control Module |
| SPOUT | Distributor Jumper to Allow Initial Timing |
| TP | Throttle Position Sensor |
Jim Oaks is the founder of TheRangerStation.com, the longest-running Ford Ranger resource online since 1999. With over 25 years of hands-on experience building and modifying Ford Rangers — including magazine-featured builds like Project Transformer — Jim has become one of the most trusted authorities in the Ford Ranger off-road and enthusiast space. In 2019, he was loaned a Ranger FX4 by Ford Motor Company to test and document across the TransAmerica Trail. Jim continues to inspire and guide Ranger owners around the world.