3 sourced reports, with what to check before you buy. Each one links to the page it was reported on.
Costly or dangerous
Instant Pot Ultra Series named in class action over defective lid-locking assembly
The Ultra Series is explicitly named in a federal class action alleging the lid-locking mechanism can fail during normal use, allowing the lid to open while contents are under pressure, causing scalding eruptions. This is a documented, litigated safety defect affecting the Ultra model.
What to check. If you own an Instant Pot Ultra, never force the lid open and always verify the float valve has dropped before opening. The lawsuit alleges the safety mechanism can fail even in normal use.
Instant Pot Ultra manual documents 'Ovht' overheating warning and pressure failure mode
The official Ultra manual documents an 'Ovht' (overheating) warning where the cooker reduces heating temperature and may fail to reach cooking pressure, potentially caused by starch deposits blocking heat dissipation from the inner pot bottom.
What to check. If the Ultra shows an Ovht warning, stop cooking and inspect the bottom of the inner pot for residue buildup. The unit may fail to reach pressure, meaning food may not be safely cooked.
Instant Pot Ultra official troubleshooting documents temperature sensor error codes C1/C2/C5
The official Instant Pot troubleshooting document explicitly covers the Ultra model and lists C1/C2/C5 error codes indicating faulty temperature sensors, requiring contacting customer care. This indicates a known electrical failure mode.
What to check. If the display shows C1, C2, or C5 codes, the unit requires service; the official guidance is to contact Instant Pot customer care rather than attempt DIY repair.
These reports come from the pages linked under each item: owner forums, repair guides and workshops. They are not a diagnosis of any one unit, and a careful check of the one you are buying still applies.
Text from the Kriko Instant Pot electric pressure cookers catalog, version 0.1.1, under the CC-BY-SA-4.0 license.
