Narrative:

Climbing out on the zzzzz departure we had made the turn from zzzzz to ZZZZZ1. ATC asked me where we were going. I interpreted this as a possible inquiry as to our destination and I replied; ZZZ. He then asked me if the previous controller had given us a direct route to ZZZ. I said; no. He then gave us a heading to fly and shortly gave us direct to the ZZZ VOR.we both immediately began a scan of our instruments to figure out our error. When the pilot flying dialed in the new assigned heading and went into heading mode; he noted that our current heading was approximately 30 degrees off of the heading depicted on the departure chart. On both pfds; the lateral deviation indicator was centered and on both mfds we were tracking a magenta course line. On both fmas LNAV was displayed in the lateral mode box. When the pilot flying typed in ZZZ and placed it on the top line of the mcdu he placed it over the ZZZZZ3 fix; which was our next fix enroute on the flight plan. Prior to that action the only time either one of us touched either mcdu was to make a radio frequency change and to call for weather at the destination airport. The flight continued to the destination with no other course deviations.the cause of the course deviation is unknown to me. All indications showed us we should have been on course.double checking the required heading vs the course depicted taking into account reasonable wind correction could possibly help in this situation only because we had a charted point of reference.

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Original NASA ASRS Text

Title: ERJ-175 Captain reported an FMC/MCDU malfunction resulting in a route clearance deviation.

Narrative: Climbing out on the ZZZZZ departure we had made the turn from ZZZZZ to ZZZZZ1. ATC asked me where we were going. I interpreted this as a possible inquiry as to our destination and I replied; ZZZ. He then asked me if the previous controller had given us a direct route to ZZZ. I said; no. He then gave us a heading to fly and shortly gave us direct to the ZZZ VOR.We both immediately began a scan of our instruments to figure out our error. When the Pilot Flying dialed in the new assigned heading and went into heading mode; he noted that our current heading was approximately 30 degrees off of the heading depicted on the departure chart. On both PFDs; the lateral deviation indicator was centered and on both MFDs we were tracking a magenta course line. On both FMAs LNAV was displayed in the lateral mode box. When the Pilot Flying typed in ZZZ and placed it on the top line of the MCDU he placed it over the ZZZZZ3 fix; which was our next fix enroute on the flight plan. Prior to that action the only time either one of us touched either MCDU was to make a radio frequency change and to call for weather at the destination airport. The flight continued to the destination with no other course deviations.The cause of the course deviation is unknown to me. All indications showed us we should have been on course.Double checking the required heading vs the course depicted taking into account reasonable wind correction could possibly help in this situation only because we had a charted point of reference.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.