Gas detection equipment won’t last forever. Many sensors typically need to be replaced every two to three years as the components degrade over time. Cross-sensitivity to non-target gases can also lead to inaccurate results, including positive and negative readings.
Troubleshoot by brand and symptom: skip to the FAQ section below for brand-specific diagnostics — RKI GX-3R error codes, BW MicroClip XL cal-fail, BW Clip 2-year end-of-life beeping, RKI GX-Force LEL poisoning, O₂ reading at 20.9%, and when to repair versus replace. The sections above cover the general causes behind each symptom.
Gas detection issues can lead to a false sense of security. These devices can malfunction for various reasons, leading to inaccurate readings and poor connectivity. All gas monitoring equipment naturally degrades over time, regardless of how often you use it. Exposing the unit to moisture, dirt, and high concentrations of gases only shortens its lifespan. You need to replace and maintain the individual components of the device to keep them working properly and the readings accurate. Other situations may require some guesswork as you determine why the instrument won’t respond. The gas detection troubleshooting process depends on the problem, age, and condition of your equipment.
Learn about some of the most common gas detection issues to keep your team safe on the job.
The Gas Detector Won’t Turn On
If the unit doesn’t respond or suddenly dies, there could be an issue with the power source. Make sure the device is set to the ON position.
For portable gas detectors, try swapping out the battery or recharging the unit. The battery will be disposable alkaline, rechargeable lithium-ion (Li-ion), or rechargeable nickel metal hydride (NiMH). Watch out for acid leaks and damage to the battery. Low temperatures can interfere with the voltage of alkaline batteries. Check the operating temperature range to see if the weather is causing the problem.
For fixed gas detectors, check the power cable for damage. Test the amount of voltage going into the device. If there’s no voltage, inspect the fuse connectors going in and out of the marshaling cabinet. Check the wiring inside the terminal block. There are usually three wires inside, which could be loose or in the wrong configuration.
A wireless gas detection system can help you stay on top of unexpected outages. You can see all the units in your network on the dashboard using the included software. The system sends you an alert as soon as a monitor goes offline.
The Gas Detector Won’t Calibrate
You need to bump test your gas detector before each shift and calibrate it if the bump test fails. OSHA and the International Safety Equipment Association (ISEA) both recommend a bump test at the start of every shift; full calibration typically occurs monthly for high-use portable monitors and quarterly for lower-use units (see the manufacturer's specification for the specific device). Both are necessary to ensure your equipment is working properly, but the calibration process checks for accuracy and it isn’t the same for every type of device. Check the manufacturer's guidelines for more detailed bump testing and calibration information, as well as calibration gas shelf life details. OSHA's guidance on this workflow lives in the Safety and Health Information Bulletin "Calibrating and Testing Direct-Reading Monitors" (reissued November 26, 2024, formerly SHIB 09-30-13), which cross-references 29 CFR 1910.146 for permit-required confined-space calibration requirements. Various environmental factors, including humidity, temperature, and air pressure, can affect the readings on the device. Perform the test as close to the worksite as possible. Calibration gas can also expire, typically after three years or less depending on if they’re reactive or nonreactive gases.
Continue gas monitor calibration, according to the instructions, until the readings on the device match the known quantity of the gas tube. Don’t use a gas detector that fails to recalibrate properly. There could be a problem with the sensor.
Sensor Error and Replacement
The sensors on your gas detector have a service life. Most last up to two or three years before they need to be replaced, regardless of how much they’ve been used. Service life varies by sensor technology: electrochemical sensors (used for O2, CO, H2S, and other toxic gases) typically last 1–3 years; catalytic bead LEL sensors last 2–3 years and can be shortened by exposure to silicones or lead compounds (permanent poisoning) or temporary inhibition from H2S/VOCs (usually recovers in fresh air); PID lamps last 1–2 years; and infrared (IR) sensors, which have no consumable elements, can last 5+ years and resist poisoning entirely. Electrochemical sensors are made with precious metals and mineral acids that generate an electric current when exposed to the target gas. These materials will break down and lose accuracy over time. When replacing the sensor, let it stabilize in ambient air for up to three hours before calibrating it by hand.
Dirt and grime can also collect in and around the sensor housing. Use a brush or compressed air to get rid of any debris that could interfere with the signal. Clean out the sensor filter to let air pass over the sensor’s surface.
For fixed gas monitors, you can also try replacing the unit transmitter if replacing the sensor doesn’t do the trick. The first sensor may be usable with another transmitter.
Sensors can malfunction for other reasons. Moisture, humidity, and changing temperatures can affect how the sensor reacts to the target gas. Look for water near where the detection is installed. Sudden changes in the air may even cause the readings to fluctuate during operation. Electromagnetic interference (EMI) from radio frequencies, such as cellphone towers and communication networks, can trigger false positives by making the sensor more sensitive. This may not put your life at risk, but it can cause unnecessary panic among the crew and delay their response to an actual emergency if they believe it’s another false alarm.
Cross-sensitivity Issues
The sensor may also be sensitive to other target gases in the air. The blending of certain gases can also affect the readings for a single target gas — also known as cross-sensitivity. Every manufacturer publishes a cross-sensitivity chart outlining how the presence of non-target gases can affect the readings on different types of gas sensors. Post this resource in the workplace or give each worker a copy they can carry around in their pocket. Teach workers how various gases can affect monitor sensitivity.
Investigating possible cases of cross-sensitivity usually requires some detective work. For example, a monitor may show positive readings for CO and H2S; however, there aren’t any in the atmosphere. Looking at the table may reveal that hydrogen cyanide (HCN) or H2 might be in the air because these gases tend to affect the readings on CO and H2S monitors.
If you get a negative reading on a gas monitor, don’t assume the equipment is broken. This usually means the sensor either needs to be recalibrated or another gas is causing the ions in the sensor to react negatively, which reads as a negative percentage. Learning cross-sensitivity is a crucial part of the training process. A slight change in accuracy can change your perception of the work environment and provide a false sense of comfort.
Gas detection equipment isn’t an exact science. Various factors can affect the readings on your equipment, which could cause workplace delays. However, learning how to troubleshoot gas detection problems helps you get as close to a perfect reading as possible.
An error can occur at any time, delaying your workday. If there’s something wrong with the device, the worker should report the issue to their supervisor and stop working until the problem is resolved. Proper gas detector repair procedures should be followed to ensure safety. Everyone should keep this information in mind when inspecting their gas detection equipment, and the crew should have time to double-check the readings on the device before starting their shift.
Contact PK Safety for gas detector calibration services and gas detection troubleshooting to get your equipment in working order. Our service department also takes direct repair orders by brand: RKI Instruments calibration service, BW / Honeywell calibration service, RAE Systems calibration service, and WatchGas calibration service. Reach the service department at 800.829.9580.
SHOP GAS DETECTION SERVICE & REPAIR
Frequently Asked Questions
What does an error code (E-11, E-12, E-13) on my RKI GX-3R mean?
Error codes on the RKI GX-3R point to specific sub-systems. E-11 and the broader E-1x family cover sensor-side faults (open sensor, bad signal, calibration drift beyond the correctable range, or a sensor at end-of-life); the full code list sits in the GX-3R Operator's Manual, chapter 7 (Troubleshooting). On any E-1x code, the first step is a fresh-air zero in known clean air, followed by a span calibration using in-date mix gas and the correct regulator. If the same code returns, the sensor module is almost certainly end-of-life — replace it with a factory RKI part, let the new sensor stabilize in ambient air for up to three hours, then calibrate. Pump and flow faults (E-20 family on pumped units) usually mean a blocked inlet filter, kinked sample line, or worn pump diaphragm. If error codes repeat after sensor swap and calibration, send the unit in for RKI Instruments calibration service — our service department diagnoses the main board, pump assembly, and firmware state as part of the flat-rate service.
Why does my BW MicroClip XL fail bump test or calibration?
The BW MicroClip XL fails bump or cal most commonly for one of five reasons: (1) expired cal gas (the four-gas mix has a shelf life of 12 months once opened, less once pressure drops below 300 psi); (2) the wrong regulator — Honeywell's cal cap and demand-flow regulator must match the sensor configuration; (3) sensor past end-of-life (the LEL catalytic bead is the typical first failure around year two in gassy environments); (4) a plugged sensor filter or hydrophobic membrane blocking gas flow; (5) in-cradle contact issues on the IntelliDoX dock. Clean the sensor filter, verify cal gas cylinder pressure and expiry, retry with a bench cal using the correct regulator. If the LEL cell still fails, replace the catalytic bead sensor and re-calibrate — if other cells also drift, the unit is at end-of-service and should be rebuilt or replaced via BW / Honeywell calibration service.
Why is my BW Clip 2-year single-gas detector beeping and showing "FAIL"?
BW Clip 2-year series (BWC2-H H2S, BWC2-M CO, BWC2-X O2) have a sealed, non-serviceable sensor and battery sized to the two-year run. Once the internal clock expires or the sensor's electrochemical cell is exhausted, the unit enters end-of-service mode: it beeps, flashes, and shows "FAIL" and will not clear with a bump test. There is no field repair path — the 2-year clip is designed as a disposable, single-cycle unit. The correct response is to replace with a fresh BW Clip of the same gas type and recycle the dead unit through Honeywell's end-of-life program. If the unit is beeping before the two-year mark, verify the activation date on the back of the case; units left in storage for more than a year before activation can reach their expiry sooner than expected.
My RKI GX-Force won't calibrate the LEL channel — what's wrong?
The RKI GX-Force's catalytic-bead LEL sensor (NCR-6309) is vulnerable to two very different failure modes. Permanent poisoning comes from silicones (silicone sprays, caulks, or sealants in the sample path), halogens, lead compounds (leaded fuels, old solder flux), and some phosphorus compounds — the catalyst is destroyed and the sensor must be replaced. Temporary inhibition comes from H2S, VOCs, or high methane spikes — the sensor usually recovers in clean air within a few hours but will fail cal while inhibited. Diagnostic step: pull the unit into known clean outdoor air for 2–4 hours, then retry the LEL span calibration with 50% LEL methane. If it passes, the sensor was inhibited and is likely fine. If it still fails, the catalytic bead is poisoned and the sensor module needs replacement. Send to RKI service for sensor swap and full re-calibration.
Why does my 4-gas monitor alarm O₂ low (or high) at 20.9%?
20.9% is the normal fresh-air oxygen concentration, so an alarm at 20.9% means the sensor's zero/span is drifted, not that the atmosphere is actually hazardous. On every 4-gas monitor (RKI GX-3R, BW MicroClip XL, BW Clip4, WatchGas SST4), the O₂ cell is calibrated to 20.9% in fresh air and then spanned to a known mix (usually ambient air for O₂). If the unit alarms at 20.9%, run a fresh-air calibration in known clean outdoor air — this corrects a drifted zero. If the alarm returns after a successful fresh-air cal, the O₂ sensor is at end-of-service (electrochemical O₂ cells typically last 1–2 years once activated, regardless of use) and should be replaced from replacement gas sensors. If the display reads 20.9% but the audible alarm fires anyway, verify the low-alarm setpoint hasn't been accidentally raised above 19.5% (the OSHA floor for oxygen-deficient atmospheres per 29 CFR 1910.146).
Why does my gas detector show negative numbers?
Negative readings almost always mean the sensor's zero point has drifted below its true baseline — it is NOT reporting a negative concentration (which is physically impossible). Three common causes: (1) the unit was zero-calibrated in a non-clean environment (trace target gas present during the fresh-air cal) and is now reading correctly in cleaner air; (2) cross-sensitivity to a non-target gas is pulling the signal down (hydrogen can suppress some CO sensors; nitrogen oxides can suppress some H2S sensors); (3) the sensor is near end-of-life and losing linearity. Fix: re-zero in verified clean air (outdoors, away from vehicle exhaust), then re-span with the correct cal gas. If negative readings persist after a clean zero and span, replace the sensor cell. Never trust a monitor showing negative numbers in a confined-space entry — pull the unit out of service until it is re-calibrated or repaired.
When should I repair my gas detector versus replace it?
The decision usually comes down to the ratio of repair cost to replacement cost over the unit's remaining useful life. Repair makes sense when the chassis, display, pump, and main board are healthy and the failure is isolated to one serviceable sensor or a tired battery pack on a multi-year serviceable monitor (RKI GX-3R, BW MicroClip XL, BW GasAlertMax XT II, GasAlert Clip4, WatchGas SST4). Our flat-rate calibration and repair service covers sensor swap, pump rebuild, and NIST-traceable cal with a certificate. Replace instead when the unit is a sealed, non-serviceable disposable (BW Clip 2-year single-gas, WatchGas SST1), when the main board or display has failed on an out-of-warranty unit, or when the model is discontinued and parts are no longer stocked. Call 800.829.9580 for a specific repair-versus-replace recommendation on your make and model before you ship.
What does "bump test due" or a blinking cal icon on my BW or RKI detector mean?
Modern detectors enforce the OSHA/ISEA pre-shift bump test by displaying a reminder when the configured bump interval has elapsed. BW units (MicroClip XL, Clip4, GasAlertMax XT II) show a "bump test due" screen or blinking icon when the IntelliDoX schedule has not fired within the preset window (default 24 hours on most Honeywell deployments). RKI units (GX-3R, GX-Force, GX-6000) show a cal/bump reminder tied to the SDM-3R or SDM-Force docking station schedule. The fix is to run a bump test in the dock (automated) or manually with a cal cap and in-date mix gas, then re-sync. The reminder is NOT an error — it's the device enforcing policy. If the dock reports a failed bump test (not just overdue), work through the failure diagnostics for that specific brand/model above before returning the unit to service, and never silence or extend the reminder past the manufacturer's recommended interval.