You are here: Ford F150 Home » How-To Technical Articles

EEC-IV Diagnostic Codes

Having problems with your truck? Need help figuring out what those diagnostic trouble codes mean? Well, look no further. These are the codes applicable to the EEC-IV processor Ford vehicles. This is generally used on 1991 - 1996 trucks and cars.

To read the EEC-IV codes, check out this article from Corral.net. If you need any further assistance, don't hesitate to post a message in the forums.

If you have a newer truck that uses EEC-V, you can get information on those codes here.

Ford EEC-IV Diagnostic Trouble Codes

Simply match up the code on the left with it's description. The code may not include the "P".

CODE	MEANING	ACTION
1 - 8	Cylinder No (as code) low power	Cylinder balance test
9	Pass	Cylinder balance test
10	Cylinder No. 1 low	Cylinder balance test
11	Cylinder No. 2 low	Cylinder balance test
12	Cylinder No. 3 low	Cylinder balance test
12	Cylinder No. 4 low	Cylinder balance test
111	All systems OK
112	Low voltage air change temperature sensor (ACT)	Normal operating temp not reached
113	High voltage air change temperature sensor (ACT)	Normal operating temp not reached
114	Out of range voltage air change temperature sensor (ACT)	Normal operating temp not reached
116	Out of range Engine coolant temperature sensor (ECT)	Normal operating temp not reached

117	Low voltage Engine coolant temperature sensor (ECT)	Normal operating temp not reached
118	High voltage Engine coolant temperature sensor (ECT)	Normal operating temp not reached
121	Outside range throttle position sensor (TPS)
122	Low voltage throttle position sensor (TPS)
123	High voltage throttle position sensor (TPS)
124	Above spec throttle position sensor (TPS)
125	Below spec throttle position sensor (TPS)
126	MAP voltage above spec
128	MAP sensor/vacuum hose fault
129	MAF sensor, no MAF change during throttle depression	Repeat self test proceedure
136	Lambda sensor (left) mixture lean
137	Lambda sensor (left) mixture rich
139	Lambda sensor (left)
144	Lambda sensor (right)
157	Low voltage mass air flow sensor (MAF)
158	HIGH voltage mass air flow sensor (MAF)
159	Outside range mass air flow sensor (MAF)
167	Throttle position sensor (TPS). No change during throttle depression	Repeat self test procedure
171	Lambda sensor (right)
172	Lambda sensor (right) too lean
173	Lambda sensor (right) too rich
174	Lambda sensor (right) slow response
175	Lambda sensor (left)
176	Lambda sensor (left) too lean
177	Lambda sensor (left) too rich
178	Lambda sensor (left) slow response
179	Fuel system lean, part throttle
181	Fuel system rich, part throttle
182	Idle mixture too lean	Idle speed control vale (ISC)
183	Idle mixture too rich	Idle speed control vale (ISC)
184	Above spec manifold air flow sensor
185	Below spec manifold air flow sensor
186	Too long injection time pulse width
187	Too short injection time pulse width
188	Lambda sensor on left, mixture too lean (part throttle)
189	Lambda sensor on left, mixture too rich (part throttle)
191	Idle mixture too lean, left hand Lambda sensor	Check EGR valve, check ISC valve
192	Idle mixture too rich, lright hand Lambda sensor	Check EGR valve, check ISC valve
193	Flexible fuel sensor circuit
194	Lambda sensor
195	Lambda sensor
211	PIP signal
212	Tach, circuit, SPOUT grounded. SPOUT circuit, open circuit
213	Tach, circuit, SPOUT grounded. SPOUT circuit, open circuit
214	CID circuit failure
215	#1 Coil
216	#2 Coil
217	#3 Coil
218	Tachometer circuit
219	Spark timing default to 10 deg	rectify SPOUT circuit
220	Tachometer circuit
221	Spark timing error
225	Knock sensor
226	EEC IV/EDIS module pulse
227	Engine speed/crankshaft position sensor (CPS)
228	EDIS module/ignition coil winding 1
229	EDIS module/ignition coil winding 2
231	EDIS module/ignition coil winding 3
232	Primary circuit of ignition coil (IGC)
233	EDIS module
234	Ignition Coil (IGC)
235	Ignition Coil (IGC)
236	Ignition Coil (IGC)
237	Ignition Coil (IGC)
238	EDIS module/ignition coil
239	PIP signal present when cranking
241	EEC IV/EDIS module, incorrect self test data	Repeat self test procedure
243	Coil failure
244	Cylinder identification fault when power balance requested
311- 316	Pulse air/thermactar air system faulty
326	Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor
327	Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor/electronic vacuum regulator (EVR)
328	Electronic vacuum regulator (EVR)
332	EGR valve not opening
334	Electronic vacuum regulator
335	Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor
336	Exhaust pressure too high
337	Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor/electronic vacuum regulator (EVR)
338	Cooling System
339	Cooling System
341	Octane adjust (service multiplug) grounded	Disconnect for self test, reconnect after
411	Engine speed during self test too low	Cure induction leaks, repeat test
412	Engine speed during self test too low	Cure induction leaks, repeat test
413 - 416	ISC valve	Cure induction leaks, repeat test
452	Vehicle speed sensor
453	Servo leaking down
454	Servo leaking up
455	Insufficient RPM increase
456	Insufficient RPM decrease
457 - 458	Speed control fault
511	ROM fault	Battery disconnected, check KAM fuse. if OK module faulty
512	Keep alive memory (KAM) fault	Battery disconnected, check KAM fuse. if OK module faulty
513	EEC IV module reference voltage V
519	Power steering pressure switch (PSPS) not activated during self test	Repeat test
521	Power steering pressure switch (PSPS) not activated during self test	Repeat test
522	Neutral/drive switch (NDS)
525	Vehicle in gear or air conditioning on
528	Clutch switch error
536	Brake on/off (BOO) switch not activated during self test	Repeat test
538	Operating error during self test. Air Conditioning switched on	Repeat test
539	Operating error during self test. Air Conditioning switched on	Repeat test
542	Fuel pump (FP) circuit failure
543	Fuel pump (FP) circuit failure
551	Idle speed control (ISC) circuit failure
552	Pulse air circuit failure
554	Fuel pressure regulator control circuit failure
556	Electrical circuit of fuel pump
557	Low speed fuel pump circuit
558	Electrical circuit of (EVR) electronic vacuum regulator
563	High speed electric drive fan relay/circuit (HEDF) failure
564	Electronic drive fan relay/circuit (EDF) failure
565	Canister purge solenoid (CANP)
566	3rd/4th gear solenoid (ATA)
573	Electronic drive fan relay/circuit (EDF) failure
574	High speed electronic drive fan relay/circuit (HEDF) failure
575	Fuel pump circuit and/or inertia switch circuit
576	Kick down switch (KDS)	Repeat test
577	Kick down switch (KDS) not activated during self test	Repeat test
583	Power to fuel pump fault
612	4/3 switch failed open circuit
613	4/3 switch failed open circuit
614	3/2 switch short circuit
615	3/2 switch failed short circuit
621	Shift solenoid 1 circuit failed
622	Shift solenoid 2 circuit failed
624	EPC solenoid failure
625	EPC solenoid circuit failure
628	MLUS Failure
629	Torque converter lock up clutch solenoid (LUS)
634	Neutral drive switch (NDS) circuit failure
635	Transmission temperature switch failure
637	Transmission temperature switch failure
639	TSS failure
645	1st gear failure
646	2nd gear failure
647	3rd gear failure
648	4th gear failure
649	ETV failure
651	ETV intermittent failure
652	MLUS circuit failure
653	Transmission control switch not activated during self test	Repeat test
998	Fault in ECT/ACT/MAF/TPR circuit