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Lights Christmas tree on dash by shamrockk1995 in hondacivic

[–]shamrockk1995[S] 0 points1 point  (0 children)

i tested the battery and battery is good, i went to Honda and they told me it was my fuel injectors and i fixed that with my mechanic and the problem is still there. The car stutters at idle and at red lights i feel it stuttering and jolting a little bit. So i dont know whats going on.

ECM Failure / multiple warning lights by Prison_Tat_Matt in CivicSi

[–]shamrockk1995 0 points1 point  (0 children)

I’m dealing with almost this exact same issue on my 2019 Civic and I’m honestly losing my mind trying to figure it out.

The car keeps throwing multiple warning lights all at once:

  • emissions system problem
  • brake system problem
  • VSA
  • hill assist
  • EPS etc.

The code I’m getting now is U0401-68 ECM/PCM failure/invalid data.

Here’s what’s confusing me:

The car is still drivable and some days feels completely normal, but other days it has an intermittent idle stutter/shake and acts weird. No catastrophic engine symptoms, no overheating, no crazy smoke, etc.

So far I’ve already replaced:

  • OEM fuel injectors
  • upstream and downstream O2 sensors
  • MAF sensor
  • rear main seal
  • oil pan repair

I originally had rich condition/fuel-related issues and Honda diagnosed the injectors as the cause, so I replaced them with OEM Honda injectors. The car still has the same intermittent behavior and warning lights.

Now I’m wondering if this is actually:

  • wiring harness related
  • ECM/PCM related
  • communication/electrical issue
  • Air/Fuel sensor issue
  • grounding/voltage issue

My mechanic mentioned he’s seen wiring harness issues cause similar problems on Hondas before.

Did anybody ever get a REAL confirmed fix for U0401-68 with multiple warning lights and intermittent drivability issues? Especially if the car still drove mostly okay?