Troubleshooting NextSeq 1000/2000 low read 1 intensity

NextSeq 1000/2000 run with low intensities on Read 1 and Index 1 which then recovers for Index 2 and Read 2 are typically caused by issues with poor priming Read 1 and Index 1.

Issues with priming can be caused by the following root causes:

  • Library design or custom primers.

  • Custom primer not proper loaded into the reagent cartridge when needed.

  • Reagent cartridge consumable quality.

Diagnosing

The Intensity Data by Cycle charts will show drops at the start of Read 1 and/or Index 1.

Troubleshooting steps:

  • Review library design, custom primers and where custom primer loaded, if applicable.

  • If run meets yield and Q30 specification, proceed with downstream analysis of the run.

  • If run does not meet yield and Q30 specification and run setup has been ruled out, contact Illumina Technical Support for the next steps.

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