EEC-IV Self-Test Codes O—Key On, Engine Off code.
CM—Continuous Memory code.
R—Engine Running code.
2-Digit Codes - 86-93 Mustangs
11 - System Pass (O,CM,R)
12 - RPM Not Within Self Test Lower Limit (R), DC Motor Did Not Move (O,CM,R), Idle Speed Control motor or Air Bypass not controlling idle properly -generally idle too low
13 - RPM Not Within Self Test Upper Limit (R), Idle Speed Control motor or Air Bypass not controlling idle properly -generally idle too high
14 - Profile Ignition Pickup Circuit Failure (CM)
15 - Readout Memory Test Failed (O), Keep Alive Memory Test Failed (CM)
16 - RPM Too Low To Perform o2 Sensor Test (R)
17 - RPM below Self-Test limit with Idle Air Control off (R)
18 - Spark Out (SPOUT) Circuit Open (R), Loss Of Ignition Diagnostic Module Input To PCM/SPOUT Circuit Grounded (CM)
19 - Failure In PCM Internal Voltage (R), Erratic RPM During Hard Idle Self Test (R), Failure in EEC reference voltage (O)
21 - Engine Coolant Temperature (ECT) Sensor Out Of Self Test Range. 0.3 to 3.7 volts(O,R)
22 - Manifold Absolute Pressure/Barometric Pressure Sensor Out Of Self Test Range (O,CM,R)
23 - Throttle Position Sensor Out Of Self Test Range (O,CM,R)
24 - Intake Air Temperature/Air Charge Temperature Sensor Out Of Self Test Range. 0.3 to 3.7 volts(O,R)
25 - Knock Not Sensed During Dynamic Response Test (R)
26 - Mass Air Flow Sensor was greater than 0.7 volts with engine off (O), MAF sensor was not between 0.2 and 1.5 volts with engine running (R).
28 - Loss Of Ignition Diagnostic Module RH Side (CM)
29 - Insufficient Input From Vehicle Speed Sensor -To 1992 (CM), Insufficient Input From Programmable Speedometer/Odometer Module -From 1993 (CM)
31 - EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage. 0.24 volts (O,CM,R)
32 - EGR Valve Position/Pressure Feedback EGR Voltage Below Closed Voltage. 0.24 volts (O,CM,R)
33 - EGR Valve Opening Not Detected (CM,R)
34 - EGR Valve Position/Pressure Feedback EGR Voltage Above Closed Limit (O,R), PFE or EVP circuit has intermittently failed above the closed limit of 0.67 volts (CM)
35 - EGR Valve Position/EGR Pressure Feedback EGR Circuit Above Maximum Voltage of 4.81 volts (O,R), PFE or EVP circuit has intermittently failed above the maximum limit of 4.81 volts (CM)
36 - System Indicates Lean At Idle (R)
37 - System Indicates Rich At Idle (R)
39 - AXOD converter bypass clutch not applying properly (CM)
41 - System Indicates Lean -passenger side(R), No o2 Sensor Switching Detected. always lean -passenger side(CM)
42 - System Indicates Rich -passenger side(R), No o2 Sensor Switching Detected. always rich -passenger side(CM)
43 - o2 Sensors indicate lean at Full Throttle (CM)
44 - Secondary Air System Inoperative. bank one, passenger side (R)
45 - Secondary Air Upstream During Self Test (R)
46 - Secondary Air Not Bypassed During Self Test (R)
47 - Measured Air Flow Low At Base Idle (R)
48 - Measured air flow too high at base idle (R)
49 - 1–2 Shift Error (CM)
51 - Engine Coolant Temperature Circuit Open (CM,O)
52 - Power Steering Pressure Switch Circuit Open (O), Power Steering Pressure Switch Circuit Did Not Change States (R)
53 - Throttle Position Sensor Circuit Above Maximum Voltage (CM,O)
54 - Intake Air Temperature/Air Charge Temperature Circuit Open (CM,O,R)
55 - Key Power Check (R)
56 - Mass Air Flow/Vane Air Flow Sensor Circuit Above Maximum Voltage (O,CM,R), MAF Sensor short to power (CM,R), Transmission Fluid Temperature Circuit Open (CM,O)
57 - AXOD Neutral pressure switch circuit failed open (CM)
58 - Idle Tracking Switch Circuit Open Or Grounded -CFI (O,R), Vane Air Temperature Sensor Input Greater Than Self Test Maximum -EFI (CM,O)
59 - 2–3 Shift Error (CM), AXOD 4/3 Pressure Switch Circuit Failed Closed (O), AXOD 4/3 Pressure Switch Circuit Failed Open (C)
61 - ECT Sensor Circuit Grounded (O,CM,R)
62 - Torque Converter Clutch Error (C,M), AXOD 4/3 Or 3/2 Pressure Switch Circuit Grounded (O)
63 - Throttle Position Sensor Circuit Below Minimum Voltage (O,CM,R)
64 - Intake Air Temperature/Air Charge Temperature Circuit Grounded (O,CM,R)
65 - Transmission Control Switch/Overdrive Cancel Switch Circuit Did Not Change States (R)
66 - , MAF signal below minimum test voltage of .4vdc (O,CM,R), Transmission Fluid Temperature Circuit Grounded (CM,O)
67 - Park Neutral Position Switch Circuit Open; A/C On -Manual (O), Manual Lever Position Sensor Out Of Range/A/C On (CM,O), Clutch Switch Circuit Failure (CM)
68 - Transmission recently overheated, or TOT sensor intermittently failed below 0.2 volts (CM)
69 - 3–4 Shift Error (CM)
71 - Software re-initialization detected or Cluster Control Assembly circuit failed (CM)
72 - Insufficient Manifold Absolute Pressure/Mass Air Flow Change During Dynamic Response Test (R)
73 - Insufficient Throttle Position Change During Dynamic Response Test (O,R)
74 - Brake On/Off Circuit Open–Not During Self Test (CM,R)
75 - Brake On/Off Circuit Closed/ECA Input Open (R)
76 - Insufficient Vane Air Flow Sensor Output Change During Dynamic Response Test (R)
77 - Operator Error Dynamic Response Test (R)
78 - Re-Initalization Check (R)
79 - A/C On/Defrost On During Self Test (O)
81 - Secondary Air Diverter Circuit Failure (O)
82 - Secondary Air Bypass Circuit Failure (O)
83 - EGR Control solenoid circuit failure (O)
84 - EGR Vacuum Regulator (EVR) Control Circuit Failure (O)
85 - CANP Circuit Failure (O)
86 - Adaptive fuel limit reached (CM), 3 – 4 Shift solenoid circuit failure (O)
87 - Primary Fuel Pump Circuit Failure (CM,O)
88 - Loss Of Dual Plug Input Control (CM), Throttle Kicker Fault (?)
89 - Converter clutch solenoid circuit failure (CM)
91 - o2 Sensor Circuit Indicates Lean -driver side(R), No o2 Sensor Switching Detected. always lean -driver side(CM), Shift Solenoid 1 Circuit Failure (O)
92 - o2 Sensor Circuit Indicates Rich -driver side(R), No o2 Sensor Switching Detected. always rich -driver side(CM), Shift Solenoid 2 Circuit Failure (O)
93 - Converter Clutch Solenoid Circuit Failure (O)
94 - Secondary Air Injection Inoperative. bank two, driver side (R), Torque Converter Clutch Solenoid Circuit Failure (O)
95 - Fuel Pump Circuit Open-PCM To Motor Ground (CM,O)
96 - Fuel Pump Circuit Open-Battery To PCM (CM,O)
97 - Transmission Control Indicator Lamp Circuit Failure (O)
98 - Hard Fault Present (R)
99 - Electronic Pressure Control Circuit Failure (CM,O)
Cylinder Balance Test Codes
10 - Cylinder #1 Failed Cylinder Balance Test
20 - Cylinder #2 Failed Cylinder Balance Test
30 - Cylinder #3 Failed Cylinder Balance Test
40 - Cylinder #4 Failed Cylinder Balance Test
50 - Cylinder #5 Failed Cylinder Balance Test
60 - Cylinder #6 Failed Cylinder Balance Test
70 - Cylinder #7 Failed Cylinder Balance Test
80 - Cylinder #8 Failed Cylinder Balance Test
90 - All cylinders passed Cylinder Balance Test
3-Digit Codes - 94/95 Mustangs
111 - System Pass
112 - ACT Sensor Circuit Below Minimum Voltage of 0.2 volts (O), ACT circuit has intermittently failed below minimum 0.2 volts (CM)
113 - ACT Sensor Circuit Above Maximum Voltage of 4.6 volts (O), ACT circuit has intermittently failed above the maximum of 4.6 volts (CM)
114 - ACT out of self test range 0.3 to 3.7 volts
116 - ECT out of self test range 0.3 to 3.7 volts
117 - ECT Sensor Circuit Below Minimum Voltage of 0.2 volts(O), ECT circuit has intermittently failed below minimum 0.2 volts (CM)
118 - ECT Sensor Circuit Above Maximum Voltage of 4.6 volts (O), ECT sensor circuit has intermittently failed above the maximum of 4.6 volts (CM)
121 - Closed throttle TPS voltage higher or lower than expected (O,R), TP sensor was inconsistent with the MAF/MAP value in the last 80 drive cycles (CM)
122 - TPS circuit below minimum 0.6 volts (O), TPS circuit has intermittently failed below minimum 0.6 volts (CM)
123 - TP circuit above maximum 4.5 volts (O), TPS circuit has intermittently failed above maximum 4.5 volts (CM)
124 - TP sensor was higher than expected with the MAF/MAP value in the last 80 drive cycles (CM)
125 - TP sensor was lower than expected with the MAF/MAP value in the last 80 drive cycles (CM)
126 - MAP/BP sensor out of self test range 1.4 to 1.6 volts
128 - MAP sensor vacuum was not greater than 2 in-Hg (7 kPa) during normal vehicle operation
129 - Insufficient MAF/MAP change during Dynamic Response Test
136 - o2 Sensor circuit indicates system lean (left side)
137 - o2 Sensor circuit indicates system rich (left side)
139 - No HEGO sensor switching detected or disconnected (left side)
141 - o2 Sensor circuit indicates system lean (both sides)
144 - No o2 Sensor switching detected or disconnected (right side)
157 - MAF sensor went below 0.4 volts during the last 80 warm-up cycles
158 - MAF sensor went above 4.5 volts during the last 80 warm-up cycles
159 - MAF signal was greater than 0.70 volt during KOEO (O), MAF signal was not between 0.20 and 1.50 volts during KOER (R)
167 - TPS did not exceed 25% rotation during the Dynamic Response Test
171 - Fuel system at adaptive limit, o2 Sensor unable to switch (right side)
172 - o2 Sensor sensor circuit indicates system lean (right side)
173 - o2 Sensor sensor circuit indicates system rich (right side)
174 - o2 Sensor switching time is slow
175 - Fuel system at adaptive limit, o2 Sensor unable to switch(left side, (Bank No. 2))
176 - o2 Sensor circuit indicates system lean (left side)
177 - o2 Sensor circuit indicates system rich (left side)
178 - o2 Sensor switching time is slow (Bank No. 1)
179 - Right side still rich, at leanest adaptive limit, during part throttle
181 - Right side still lean, at richest adaptive limit, during part throttle
182 - Right side still rich, at leanest adaptive limit, at idle
183 - Right side still lean, at richest adaptive limit, at idle
184 - MAF higher than expected
185 - MAF lower than expected
186 - Injector pulse width longer than expected
187 - Injector pulse width shorter than expected
188 - Left side still rich, at leanest adaptive limit, during part throttle
189 - Left side still lean, at richest adaptive limit, during part throttle
191 - Left side still rich, at leanest adaptive limit, at idle
192 - Left side still lean, at richest adaptive limit, at idle
193 - Flexible Fuel sensor circuit failure
194 - Run cylinder balance diagnostic test
195 - Run cylinder balance diagnostic test
211 - Two or more successive erratic Profile Ignition Pickup (PIP) pulses occurred, resulting in a possible engine miss or stall
212 - Loss of IDM (Ignition Diagnostic Monitor) input to EEC or SPOUT circuit grounded
213 - SPOUT circuit open
214 - Cylinder Identification (CID) circuit failure
215 - EEC detected coil 1 primary circuit failure
216 - EEC detected coil 2 primary circuit failure
217 - EEC detected coil 3 primary circuit failure
218 - Loss of IDM (Ignition Diagnostic Monitor) signal (left side)
219 - SPOUT failure, spark timing has defaulted to 10 degrees BTDC
222 - Loss of IDM (Ignition Diagnostic Monitor)signal (right side)
223 - Loss of Dual Plug Inhibit control
224 - Erratic IDM (Ignition Diagnostic Monitor)input to processor
225 - Knock Sensor (KS) signal not sensed during dynamic response test
226 - IDM (Ignition Diagnostic Monitor)signal not received
244 - Camshaft Position (CMP) Sensor failure
311 - Thermactor air system inoperative (right side)
312 - Thermactor air misdirected upstream during self test
313 - Thermactor air not bypassed during self test
314 - Thermactor air system inoperative (left side)
326 - PFE or DPFE circuit voltage lower than expected with zero EVR duty cycle
327 - DPFE or EVP circuit below minimum voltage of 0.2 volts
328 - EVP circuit below minimum voltage of 0.24 volts
332 - EGR valve opening not detected
334 - DPFE or EVP circuit above the closed limit of 0.67 volts
335 - PFE or DPFE sensor voltage out of Self-Test range
336 - EVP or DPFE circuit voltage above maximum voltage with zero EVR duty cycle
337 - DPFE or EVP circuit above the maximum limit of 4.81 volts
338 - ECT lower than expected
339 - ECT higher than expected
341 - Octane Adjust shorting bar is not in or the OCT ADJ circuit is open
381 - Frequent A/C compressor clutch (ACCS) cycling less than 8.5 seconds
411 - Cannot control rpm during KOER low RPM check
412 - Cannot control rpm during KOER high RPM check
452 - Computer detected an error in the VSS or PSOM signal during the last 80 warm-up cycles
461 - Engine over speed was detected
511 - EEC permanent Read Only Memory (ROM) test failed
512 - EEC battery powered Keep Alive Memory (KAM) test failed
513 - Failure in EEC processor internal voltage
519 - Power steering pressure switch circuit open
521 - Power steering pressure switch did not change state during KOER test
522 - Vehicle not in PARK or NEUTRAL during KOEO
524 - When the PCM commanded the fuel pump on, voltage was not detected on FPM
525 - Vehicle in gear or A/C on during Self-Test
526 - Neutral Pressure Switch closed or A/C on
527 - Neutral Drive Switch open or A/C on
528 - Clutch Switch Circuit failure
529 - Data Communications Link or Electronic Instrument Cluster circuit failure
532 - Data Communications Link or Electronic Instrument Cluster circuit failure
533 - Data Communications Link or Electronic Instrument Cluster circuit failure
536 - Brake On/Off circuit failure / switch not actuated during KOER test
538 - Insufficient RPM change during KOER dynamic response test/ Operator error
539 - A/C or Defroster ON during KOEO test
542 - Fuel pump circuit failure
543 - When the PCM commanded the fuel pump on, voltage was not detected on FPM
551 - Intake Manifold Runner Control (IMRC) circuit failure
552 - Air management 1 circuit failure (AM1/TAB)
553 - Air management 2 circuit failure (AM1/TAD)
554 - Fuel Pressure Regulator Control (FPRC) solenoid circuit failure
556 - Fuel Pump circuit failure
557 - Fuel pump relay coil resistance failure
558 - EGR Vacuum Regulator circuit failure
559 - Air Conditioning On relay circuit failure
563 - High Speed Electro-Drive Fan circuit failure
564 - Electro-Drive Fan circuit failure
565 - Canister purge circuit failure
566 - 3 – 4 Shift Solenoid failure
569 - Canister purge 2 circuit failure
571 - EGR Atmospheric Regulator circuit failure
572 - EGR Vacuum Regulator circuit failure
578 - A/C Pressure (ACP) sensor VREF circuit is short to ground
579 - A/C Pressure (ACP) sensor circuit is above maximum voltage
581 - When the cooling fan was activated, the circuit exceeded current draw
582 - Open or short to power in the power-to-cooling fan circuit
583 - When the fuel pump was activated, the power-to-pump circuit exceeded the normal current draw
584 - Variable Control Relay Module circuit grounded
585 - A/C clutch circuit exceeded the normal current draw
586 - A/C clutch circuit open or shorted to power
587 - Data Communications Link (DCL) error
593 - Oxygen Sensor Heater circuit failure
617 - 1 - 2 shift error (E4OD)
618 - 2 - 3 shift error (E4OD)
619 - 3 - 4 shift error (E4OD)
621 - Shift solenoid #1 circuit failure
622 - Shift solenoid #2 circuit failure
623 - Overdrive light circuit failure
624 - Electronic Pressure Control solenoid or driver circuit failure
625 - Electronic Pressure Control driver open in EEC
626 - Coast clutch solenoid circuit failure (E4OD)
627 - Converter clutch solenoid circuit failure (E4OD)
628 - Converter clutch Lock-Up error (E4OD)
629 - Converter clutch control circuit failure
631 - Overdrive light circuit failure
632 - Overdrive cancel switch not changing state (E4OD)
633 - 4WD switch is closed
634 - Transmission Manual Lever Position Sensor circuit out of self test
636 - TOT sensor voltage out of self test range
637 - TOT sensor circuit above maximum voltage
638 - TOT sensor circuit below minimum voltage
639 - Insufficient input from the Transmission Speed Sensor
641 - Shift solenoid #3 circuit failure
643 - Converter Clutch Control circuit failure
645 - Incorrect gear ratio obtained for first gear
646 - Incorrect gear ratio obtained for second gear
647 - Incorrect gear ratio obtained for third gear
648 - Incorrect gear ratio obtained for fourth gear
649 - Electronic Pressure Control range failure
651 - Electronic Pressure Control circuit failure
652 - Modulated Converter Clutch Control solenoid output circuit error
653 - Transmission Control Switch was not cycled during KOER Self-Test
654 - MLP sensor not in park position
656 - Converter Clutch Control continuous slip error detected
657 - Transmission over temperature condition occurred
659 - High vehicle speed detected while the vehicle was in PARK
667 - Transmission Manual Lever Position Sensor circuit shorted
668 - Transmission Manual Lever Position Sensor circuit open
675 - MLP circuit voltage was out of the expected range
691 - 4WD switch circuit failure
998 - Hard fault present