Description
Thermo Scientific 42iQ NOx Gas Analyzer Repair
The 42iQ measures NO, NO2 and NOx by chemiluminescence, covering sub-ppb levels up to 1000 ppb in the trace-level configuration, with preset ranges from 0 to 0.05 ppm through to 20 ppm and low-source and high-level variants alongside. It sits in the iQ Series platform, with predictive diagnostics, a 7 inch color touchscreen and remote access through ePort. These run continuously in regulatory monitoring networks, so the failures we see are wear failures, not accidents.
June Company’s certified technicians repair the 42iQ for air quality monitoring networks, environmental agencies, emissions testing contractors and industrial compliance teams. We diagnose and repair at the board and component level, and every instrument is functionally verified before it ships back.
Common 42iQ problems we fix
- PMT detector faults — photomultiplier sensitivity falling, which raises detection limits and drifts the span.
- PMT cooling faults — detector cooling losing performance, which raises noise and undermines trace-level work first.
- Ozonator faults — ozone generation dropping, which reduces response across the whole measurement.
- NO2-to-NO converter faults — converter efficiency falling, which biases NO2 and NOx while NO still reads correctly.
- Sample pump faults — worn pumps reducing flow, which changes response time and calibration.
- Flow control and sensor faults — mass flow readings drifting, which quietly biases concentration.
- Reaction chamber contamination — deposits in the chamber raising background and reducing sensitivity.
- Calibration and span drift — the analyzer failing zero and span checks, which is a compliance failure as much as a technical one.
- Touchscreen and interface faults — unresponsive panels on the 7 inch iQ Series display.
- Communication faults — ePort, network or data logger connections dropping, which loses monitoring data.
FAQs
NO reads correctly but NO2 does not. What is that? That pattern points at the converter rather than the detector, because NO bypasses it. It is one of the more useful symptoms this analyzer produces and it narrows the job immediately.
Can you test converter efficiency? Yes, and we do it as standard on any 42iQ. Converter efficiency is the fault most often missed when an analyzer is simply recalibrated.
Do you handle the 42i and other iQ Series analyzers? Yes, including the 48iQ and 49iQ, and the older i Series.
Every repair is backed by a 90-day parts-and-labor warranty, with a firm quote before any work begins. Email us or submit a service request.








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