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Ford E350 5.4L P0171 and P0351-P0358 Ignition Coil Failure: Diagnosis and Fixes

Model: Ford E350 5.4L Fault Code: P0171 Posted: 2017-04-13 04:32

My 2001 Ford E350 5.4L engine is showing multiple OBD-II fault codes: P0171 (Rich Air-Fuel Mixture - Bank 1) and P0351 through P0358 (Ignition Coil A to H primary/secondary circuit faults). I believe this indicates all eight ignition coils are faulty. The vehicle starts but runs for only about one minute before shutting down abruptly. I've recently replaced spark plugs, fuel filter, air filter, and fuel pump, yet the issue persists. No other diagnostic codes appear after clearing them. The engine starts with a full 12V at both ignition coils and injectors during key-on, engine-off (KOEO) test. After clearing the codes and starting the engine, it runs for one minute before shutting off. I have no remote starter or alarm system installed. I'm seeking advice on whether this is truly a coil failure or if there's an underlying wiring issue or sensor problem.

Related fault codes
P0171
Comments (7)
Anonymous 2017-04-13 07:45

Are there any additional fault codes besides P0171 and the P035x series? Any recent modifications or repairs? Is the vehicle stock (no remote starter, alarm, or performance upgrades)? Let's focus on ignition coils first — does the engine start at all? Eight failing coils simultaneously is highly unlikely; a wiring issue or sensor fault is more probable. Check for 12V at the coil terminals (RD/LG) during KOEO.

Anonymous 2017-04-13 11:57

I recently replaced spark plugs, fuel filter, fuel pump, and air filter. After these changes, the same issue occurred — engine runs for about one minute before shutting down completely.

Anonymous 2017-04-13 13:21

Is the vehicle stock with no remote starter or alarm system? Are there any other diagnostic codes present? Have you replaced spark plugs, fuel filter, fuel pump, or air filter — and did this happen before or after the shutdown began? A quick test: during KOEO, is there 12V at both ignition coils and injectors?

Anonymous 2017-04-13 16:03

The engine was already shutting down prior to any part replacements. I confirmed 12V at both ignition coils and injectors during the KOEO test.

Anonymous 2017-04-13 16:07

I cleared the codes and started the engine — it ran for about one minute before shutting off. Then I reinstalled the old spark plugs, and after waiting two hours, no new codes appeared. No code was detected during subsequent checks.

Anonymous 2017-04-13 16:08

I used an OBD-II scanner to check for active codes — no faults were reported after clearing them.

Anonymous 2017-04-13 16:31

Is the vehicle stock with no remote starter or alarm? Confirmed: KOEO shows 12V at both ignition coils and injectors. The engine starts and runs for about one minute before shutting down. Next step: check fuel pressure using a gauge — this could indicate a fuel delivery issue. Also, inspect the CKP (Crankshaft Position) sensor signal for proper operation.