B737 captain reported the autopilot overshot an assigned altitude during climb.

Attributes
ACN	1752100
Time
Date	202007
Local Time Of Day	1201-1800
Place
Locale Reference	D01.TRACON
State Reference	CO
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 150 Flight Crew Type 10000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance

Narrative:

Climbing out of denver; the aircraft failed to level off at kidng at or below the 10;000 ft. Restriction. LNAV and VNAV were selected and MCP showed LNAV/VNAV speed. The 10;000 ft. Restriction was still in the FMC; it was never deleted. I watched it climb right through 10;000 ft. And continue to climb. I punched off the autopilot and pushed us back down to 10;000'. At that point the flight director was obviously holding 10;000 ft.; so I put the autopilot back on and then it started climbing after the kidng restriction. We peaked at 10;700 ft. Four miles prior to kidng. ATC never called us and didn't seem to notice. I didn't write the malfunction up because there were no other problems and that was our third leg in the aircraft. I told the next captain about the glitch and told him to keep an eye on it.it seems to have been a glitch by the autopilot. I've seen lots of VNAV confusion in the past; but I've never seen it blow through an altitude.

Original NASA ASRS Text

Title: B737 Captain reported the autopilot overshot an assigned altitude during climb.

Narrative: Climbing out of Denver; the aircraft failed to level off at KIDNG at or below the 10;000 ft. restriction. LNAV and VNAV were selected and MCP showed LNAV/VNAV SPD. The 10;000 ft. restriction was still in the FMC; it was never deleted. I watched it climb right through 10;000 ft. and continue to climb. I punched off the autopilot and pushed us back down to 10;000'. At that point the flight director was obviously holding 10;000 ft.; so I put the autopilot back on and then it started climbing after the KIDNG restriction. We peaked at 10;700 ft. four miles prior to KIDNG. ATC never called us and didn't seem to notice. I didn't write the malfunction up because there were no other problems and that was our third leg in the aircraft. I told the next Captain about the glitch and told him to keep an eye on it.It seems to have been a glitch by the autopilot. I've seen lots of VNAV confusion in the past; but I've never seen it blow through an altitude.

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.