i-STAT Simulator Failure: Is It the Analyzer, Simulator, or Cartridge Lot?

When an i-STAT 1 handheld shows ELECTRONIC SIMULATOR FAIL, many point-of-care testing (POCT) and biomed teams immediately box up the analyzer and request a repair. Abbott's own documents suggest stopping first. The System Manual says an analyzer may occasionally fail a simulator test even though it is in proper operating condition, because the test is extremely sensitive. It also says an external simulator can itself malfunction, for example after being dropped, and that high humidity can fail the electronic test. Internal simulator failures add a third suspect. The internal check runs while the analyzer's connector pins touch the cartridge's contact pads, so contaminated pads, or a problem with the cartridge lot, can produce the FAIL.

This guide covers only the i-STAT 1 analyzer and these document revisions: System Manual file 014331-00_66_A (Section 5, art 714367-00J, Rev 17-Feb-2023; Quality Control section, art 714376-00AC, Rev 20-Dec-2024), Technical Bulletin 714260-00AA (Rev 27-Feb-2023), User Guide 714254-00AD (Rev 20-Mar-2024), and Abbott's Support Guide REF-1151 Rev C (effective 27-Jan-2021). Older manual revisions with different code lists still circulate online, so check your current bulletin before relying on any code mapping. This article does not decide when patient testing may resume. That is a decision for the laboratory director under CLIA and your accreditation requirements.

The Electronic Simulator, whether external or internal, is a quality-control device for the analyzer's cartridge signal-reading function. According to Abbott, it simulates two levels of electrical signals that stress the analyzer's signal detection below and above measurement ranges. This gives an independent check of how the analyzer measures voltage, current and resistance against limits specified in the analyzer software. In the System Manual's verification tables, these checks cover the voltage measuring system for potentiometric sensors, the current measuring system for amperometric sensors, the resistance measuring system for conductometric sensors, and the thermistors that control chip temperature.

What the simulator does not check matters just as much. It stands in for a cartridge, so it never tests a real cartridge's sensors, its fluids, or the patient sample. That is why the manual's checklist for out-of-range controls lists a simulator PASS as just one item, next to the expected-value insert, expiration dates, and storage conditions.

The two versions run differently. The external simulator is a stable electronic device inserted into the cartridge port, and its test cycle takes about 60 seconds. The internal simulator runs automatically when a cartridge is inserted after the customized interval has passed, adding about 20 seconds to the testing cycle. The System Manual's customization table lists the factory default for the internal simulator as a 24-hour interval with lockout, but sites can change both the interval and the lockout setting. With lockout, the analyzer keeps running the internal check and displays FAIL on each later cartridge until a test passes. Without lockout, it does not repeat the internal check until the next scheduled time. Abbott cautions that in this warn-only configuration the analyzer keeps starting test cycles.

Even with the internal simulator enabled, Abbott says an external simulator is still needed:

• To validate an internal simulator failure. An internal FAIL is a reason to test the analyzer with the external device, not a conclusion by itself.

• To reset the internal simulator schedule when an automatic simulator test might interrupt testing. Abbott's example is a cardiovascular operating room.

• For on-demand testing at any time, including during the cross-runs described below.

• To perform the thermal probe check, which is completed only with the external simulator.

A log entry such as “analyzer 3 failed simulator” cannot later show whether the fault followed the handheld, the simulator, or the consumables. Abbott's Technical Services prompts for each simulator code ask for exactly these identities: the analyzer serial number, the serial number of the external simulator that produced the code, whether the test has been repeated, and, for internal codes, the cartridge type and lot, whether the code occurs on one analyzer or several, and how many times it has occurred. Capture them when the failure happens:

The analyzer stores simulator results as distinct records that can be transmitted to the data manager, and it stores Quality Check Codes with other test records. A site with a data manager can therefore usually rebuild the history instead of relying on memory. Put these identities on the work order itself. Our guide to medical equipment service records covers what that record should contain.

When an external test fails, the analyzer shows a letter with the FAIL result. Technical Bulletin 714260-00AA defines the letters, and for each one its own instruction is to contact i-STAT Technical Services or your local support organization. The first responses in the table come from the System Manual and from Abbott's Support Guide, which sets out the troubleshooting Technical Services works through before deciding what to replace.

Numeric Quality Check Codes are separate from the letters. The bulletin pairs each one with a cause message and an action message. It says the codes are stored in analyzer memory with other test records and transmitted to the Central Data Station, and that the code is essential information when you contact support. Several codes are directly relevant to simulator failures:

• Codes 58–62 (Analyzer Error / Use Electronic Simulator): if the analyzer passes the simulator, keep using it. If it does not pass, check the battery voltage and test the analyzer with another simulator to rule out a simulator problem. Contact support if the code persists.

• Codes 47 and 48: the cartridge or simulator may not be pushed all the way in, or may have gone in at an angle. Reinsert it straight before suspecting the analyzer.

• Codes 23 and 49 (Poor Contact Detected): poor contact between the analyzer pins and the cartridge contact pads. Abbott says this can sometimes be corrected with its ceramic conditioning cartridge.

If your site uses the ceramic conditioning cartridge, know how a conditioning run ends. In the bulletin's procedure, you first run an external simulator if the internal simulator is enabled, then run the conditioning cartridge twice. The analyzer treats the conditioning cartridge as an external simulator and shows a simulator failure code such as rRGL at the end. Abbott says this is expected and the code should be disregarded. Logging it as a real simulator failure would corrupt the evidence trail.

For persistent external simulator codes, Abbott's Support Guide uses a simple method. Repeat the external test. Then rerun the same simulator on a different analyzer, or run a different simulator on the same analyzer. If only one analyzer and one simulator are available, set the analyzer to run the internal simulator with lockout enabled, and use that result to tell the two apart. The guide's note sets the internal schedule to every patient test for this purpose. The table below maps each observation to the outcome the documents give.

For internal failures, the customer System Manual adds practical steps. With lockout enabled, rerun the cartridge in the same analyzer to rule out a one-time spike of electrical noise. If it fails again, rerun it in another analyzer if one is immediately available, but not if more than three minutes have passed since the cartridge was filled. If the cartridge fails in more than one analyzer, use another cartridge. Without lockout, rerun the cartridge in another analyzer if one is available, then verify the first analyzer with an external simulator. The same decisions as a flow:

flowchart TD
    A["Simulator FAIL on an i-STAT 1"] --> B["Record analyzer serial, Simulator ID, cartridge lot and code"]
    B --> C{"External or internal test?"}
    C -->|External| D["First response: reinsert straight, check blue cap; for L wait 30 min"]
    D --> E["Repeat external test"]
    E -->|PASS| F["Record cause and result; follow site SOP"]
    E -->|FAIL again| G{"Second analyzer or simulator available?"}
    G -->|Yes| H["Cross-run: same simulator on another analyzer, or another simulator on this analyzer"]
    H -->|Simulator fails on several analyzers| I["Replace the simulator"]
    H -->|Only this analyzer fails| J["Contact Abbott: analyzer repair or replacement"]
    G -->|No| K["Internal simulator with lockout on next cartridge"]
    K -->|Internal PASS| I
    K -->|Internal FAIL| J
    C -->|Internal| L["Run external simulator on that analyzer"]
    L -->|FAIL| J
    L -->|PASS| M{"G or L above allowable rate on one lot across passing analyzers?"}
    M -->|Yes| N["Lot investigation with Abbott; check liquid controls"]
    M -->|No| O["Analyzer usable; keep counting codes by lot and box"]

The lot question comes up when analyzers pass the external simulator but internal checks keep failing with G or L during cartridge runs. Abbott's Support Guide treats an internal G or L failure as possibly analyzer-related or cartridge-related. It asks for the cartridge type and lot, whether the code appears on one analyzer or several, how many codes have occurred, whether they came from the same box, how many cartridges from that lot were used in total, and whether lockout is enabled.

The guide gives an allowable error rate of about 2–3 percent, or no more than 3 failures from an individual box. Below that rate, Abbott treats the incident as resolved. Above it, for a specific lot on multiple analyzers that pass the external simulator, the suspect lot should be investigated, and Abbott may ask whether cartridges are available for return. This threshold comes from Abbott's Technical Services reference and applies only to internal simulator G and L codes on a cartridge lot. Do not apply it to external simulator codes or to other analyzers.

To work out the rate, divide the internal G and L codes recorded for the lot by the total cartridges from that lot used over the same period, and count codes per box separately. For example, 4 internal G codes across 160 cartridges from one lot is 2.5 percent, within the guide's 2–3 percent allowance. But if all four came from one box, that box exceeds the no-more-than-3 count, and support will ask about exactly that kind of detail. Both numbers come from stored test records or the data manager. If your site has no code history, it cannot produce them reliably, and support should be told so.

The next check is liquid controls, not the simulator. In the User Guide's workflow for unexpected results, you repeat the test with a fresh cartridge and sample, then test the lot with control solutions. In-range controls suggest interference with the sample rather than a lot problem. Out-of-range controls point to the cartridge lot, and Abbott directs users to another lot number or another method. Before you conclude that controls are out of range, the System Manual's checklist has you confirm the correct expected-values insert and cartridge lot listing, the cartridge and control expiration dates, room-temperature expiration, storage and handling, and a passing Electronic Simulator test. Whether and how to restrict an affected lot is a laboratory decision. The guide to calibration verification after repair covers the separate CLIA question of when a repaired analyzer needs verification.

According to the System Manual, i-STAT analyzers have a thermal control subsystem with two thermal probes that keep the sensors, and the fluids touching them, at the required temperature. The probes are checked each time the external simulator is used. That check finishes only if the simulator's surface temperature is stable, so Abbott recommends verifying the thermal probe check every six months. The MQSI adds that it can be done together with software updates.

The documented procedure works like this. If the analyzer and simulator were stored in areas whose temperatures differ by more than 3 °C (5 °F), let them stand together, out of drafts, for 30 minutes before inserting the simulator, and handle the simulator as little as possible. When results appear, press the period key to see the difference between the probes. A value from -0.1 to +0.1, inclusive, is acceptable. Repeat the procedure if you see a FAIL with code t, a value outside that range, or a --.-- display. For --.--, Abbott notes it may help to insert the simulator partway and let it stand for 15 minutes before pushing it fully in. If the repeat also fails, contact support. Do not attempt any adjustment yourself.

Software updates are a separate gate. The MQSI says to update the system software as provided by Abbott, check the handheld with the external simulator after the update, and verify the thermal probe reading. Record the software version before and after the update, since it is also on Abbott's support information list.

Abbott's User Guide and System Manual list the information to have ready for the support representative. Here it is as a checklist, with where to find each item:

1. Description of the problem: what the screen showed and during which activity (scheduled simulator test or cartridge run).

2. When it first occurred and what has been done so far: repeat tests, first responses, cross-runs, and the result of each.

3. Serial numbers of the components: the analyzer and the external simulator (the Simulator ID entered at the test).

4. Cartridge lot number: with the cartridge type.

5. Lot numbers of i-STAT liquid quality controls or calibration verification materials: for any controls already run.

6. Displayed message and code number: the letter code and any Quality Check Code, exactly as shown.

7. Frequency of the problem: for internal codes, ideally as counts per lot and per box.

8. Software version: from the Analyzer Status page.

9. Environmental conditions: including any recent move between cold and warm areas.

10. Result of the last Electronic Simulator test: with its date and the simulator used.

11. Battery voltage: from the Analyzer Status page.

Abbott's Support Guide uses this information to classify each event in its own internal categories. A laboratory does not need to adopt those categories. What the laboratory controls is whether the packet is complete when the call starts. If an analyzer or simulator does go back, the same packet supports your service provider qualification records and the return-to-service evidence that follows.

A simulator PASS shows that the analyzer's signal-reading function met Abbott's limits. It does not show that a cartridge lot, the control materials, or an operator's technique are performing correctly, and it does not settle a laboratory's quality-control obligations on its own. Under US federal rules, those obligations depend on how the test is categorized:

• Waived testing: 42 CFR 493.15(e)(1) requires laboratories eligible for a certificate of waiver to follow manufacturers' instructions for performing the test. For the i-STAT 1, Abbott's Manufacturer's Quality System Instructions (MQSI) include checking each handheld with the Electronic Simulator, internal or external, once on each day of use. The User Guide adds verifying new, repaired or replacement analyzers with the simulator before use.

• Non-waived testing, complete process: 42 CFR 493.1256(a) makes the laboratory responsible for control procedures that monitor the accuracy and precision of the complete analytic process.

• Non-waived testing, frequency: unless CMS approves an equivalent quality testing procedure, 493.1256(d)(2) requires control procedures at the number and frequency specified by the manufacturer or established by the laboratory, when those meet or exceed the minimums in (d)(3). For quantitative procedures, those minimums include two control materials of different concentrations at least once each day patient specimens are assayed.

• After a repair: 493.1256(d)(6) requires control material testing before resuming patient testing when, among other triggers, any critical part that may influence test performance is replaced.

• Documentation: 493.1256(g) requires the laboratory to document all control procedures performed.

Abbott adds one point that helps with accreditation work: all analyzers that pass the Electronic Simulator test are equivalent. Any representative number of passing analyzers may therefore be used for initial performance verification studies, calibration verification, proficiency testing, and method comparison studies. That statement covers those procedures only; it does not replace control testing. Other bench simulators have similar limits, as discussed in pulse oximeter simulator testing. For deciding what testing a repair triggers, see return-to-service testing after a major repair.

Abbott's caution is explicit: do not open the analyzer or any other i-STAT product, and do not perform unauthorized procedures. Opening any i-STAT product, including the analyzer, Electronic Simulator, printer or communication device, to try to repair it may cause erroneous results. If the manual's troubleshooting, or procedures requested by an i-STAT support specialist, do not resolve the problem, the product must be returned to i-STAT for repair. Every step in this article happens outside the housing: repeat tests, insertion checks, equilibration, cross-runs, the internal-simulator fallback, and code counting.

Local protocols can be stricter than Abbott's baseline without changing it. The US Air Force Critical Care Air Transport clinical practice guideline (updated 26-Feb-2025) runs the external simulator when the device prompts or every 8 hours while in use, describes a test of roughly 120 seconds, and removes from service any analyzer that fails a simulator check twice. Those rules were written for air transport. Where your accredited SOP is stricter, follow it, and use Abbott's documented isolation steps to decide which component actually goes back.

Abbott publishes no simulator or analyzer failure rates, and we found no independent dataset, so this article cannot say how often a FAIL comes from the simulator rather than the analyzer. The Support Guide is an Abbott Technical Services reference (Rev C, effective 27-Jan-2021) that predates the current customer documents. We use it here only to explain the isolation logic, so confirm with Abbott that its rules still apply.

• i-STAT 1 System Manual, US English (014331-00_66_A) — Section 5 Electronic Simulator (art 714367-00J, Rev 17-Feb-2023) and Quality Control (art 714376-00AC, Rev 20-Dec-2024). Simulator purpose and cycle times, internal simulator customization and lockout, failed-test troubleshooting, the thermal probe check, MQSI, the equivalence of passing analyzers, and the do-not-open caution.

• Analyzer Coded Messages, Technical Bulletin (art 714260-00AA, Rev 27-Feb-2023) — Quality Check Code structure, codes 47/48, 23/49 and 58–62, simulator letter codes, and the ceramic conditioning cartridge procedure.

• i-STAT Support Guide REF-1151 Rev C (effective 27-Jan-2021) — Technical Services prompts and resolution logic for internal and external simulator codes, the single-analyzer fallback, and the allowable internal G/L rate for a cartridge lot.

• i-STAT 1 User Guide (art 714254-00AD, Rev 20-Mar-2024) — The support information list, Analyzer Status readings, the check for new, repaired or replacement analyzers, and the workflow for unexpected results.

• 42 CFR 493.15 Laboratories performing waived tests — Certificate-of-waiver laboratories must follow manufacturers' instructions for performing the test.

• 42 CFR 493.1256 Standard: Control procedures — Complete-process control, manufacturer-specified frequency subject to regulatory minimums, controls before resuming testing after a critical part is replaced, and documentation.

• i-STAT Portable Blood Analyzer in Austere Locations, Critical Care Air Transport Clinical Practice Guideline (update 26-Feb-2025) — An example of a stricter local protocol: an 8-hour simulator schedule, a roughly 120-second test, and removal after two failed checks.