Intoxilyzer Calibration Check Fails or Reads 0.000 With No Error Code

What's happening

A calibration check runs a known alcohol standard through the instrument and compares the result to that standard. When it fails with no exception message, the instrument is telling you it worked correctly and did not see what it expected to see. That points away from the instrument and toward everything between the cylinder and the fuel cell: the gas, the regulator, the mouthpiece, and the number you told the instrument to expect.

This guide covers those. If the screen shows an E-code, that is a different situation with its own answers in our E1 through E7 guide. If the air blank itself will not settle at 0.000 before you ever introduce the standard, start with the air blank guide instead.

First, read the result you got

The number on a failed check is the diagnosis. Three different results mean three different things.

• 0.000 on the standard. No alcohol reached the fuel cell. The instrument is fine; the gas did not get there. This is a delivery problem and it is nearly always fixable on the spot.
• A low but non-zero reading, below the lower limit the instrument displayed before the check. Some alcohol arrived, but not enough. Think flow, leak, or a depleted or expired standard.
• A reading that misses in either direction with a standard you trust. Confirm the stored standard value below before assuming the instrument has drifted.

The mistake that guarantees a fail: the stored standard value

During the check, the instrument shows you the standard value it currently has stored, and CMI's Operator's Guide is explicit: if that value does not agree with the calibration value you intend to use, adjust it before continuing. The instrument then displays the programmed standard, the barometric pressure, the pressure-corrected standard, and the upper and lower acceptability limits it will judge against.

Here is the trap. Cylinders come in several values (0.040, 0.080, and 0.100 are the common ones), and the stored value stays whatever it was last set to. Put a 0.040 cylinder on an instrument still storing 0.080 and the check will fail every time, reading roughly half of what the instrument expects, with nothing wrong anywhere. This is the single most common cause of a "routinely failing" instrument that tests perfectly at our bench. Before you introduce the gas, confirm the stored value matches the value printed on the cylinder.

One thing you do not need to correct for: altitude. The instrument has its own barometric pressure sensor and adjusts a dry gas standard automatically, so enter the cylinder's labeled value, not a locally adjusted one.

Reads 0.000: get the gas to the instrument

1. Check the cylinder has gas in it. Small cylinders run out sooner than people expect, especially if the regulator was left locked open after a previous check, which bleeds the whole cylinder. A cylinder that feels light and makes no sound at the regulator is empty.
2. Check the expiration date printed on the cylinder. Dry gas standards expire. An expired cylinder is not a known standard, and a check run against it is not valid for your records even if it passes.
3. Confirm the regulator is actually delivering. Press the button with the cylinder connected and listen for flow. No flow means a regulator problem or an empty cylinder. Check the regulator adapter is seated on the mouthpiece end as well.
4. Use a new mouthpiece, seated and locked. The manual calls for a fresh mouthpiece for every calibration check, locked in place between the two mouthpiece locators, with the standard introduced through the wide-bore, lipped end. A mouthpiece sitting loose lets gas escape before it reaches the sampling port.
5. Get the timing right. CMI's procedure is specific: let the vapor flow into the instrument for five seconds, then press the sample button while the vapor is still flowing, and keep it flowing for another second or two. Pressing the button and then starting the gas, or stopping the gas before the sample is taken, produces exactly the low or zero result you are trying to fix.
6. Make sure the sampling port is not blocked. The manual lists this among its don'ts for a reason; a blocked port starves the fuel cell.

Run the check again. A 0.000 that becomes a passing result after one of these was the whole problem.

Low but not zero

Alcohol reached the fuel cell, just not at the concentration the standard claims. Work the same list, with attention to three things: a cylinder near the end of its gas, where pressure and delivery drop off; an expired cylinder; and a leak at the mouthpiece or regulator adapter. Also confirm the instrument is within 59°F to 95°F. That range is enforced for calibration, and a cold instrument on a winter morning will read low on a good standard.

When the check fails on a standard you have confirmed

If the stored value is right, the gas is fresh and flowing, the mouthpiece is seated, and the check still lands outside the displayed limits, the instrument has drifted and needs a calibration adjustment. The manual's own sequence is: a check that fails means the instrument must be recalibrated, then a check is run again to verify the adjustment. Adjustment is a separate routine from the check and is normally something we perform for you. If the instrument refuses to adjust, it will say so with an E3, and that is a fuel cell at the end of its life rather than anything about your gas.

A note on your records

CMI recommends checking calibration at least once a month. A check that passed against the wrong stored value, an expired cylinder, or a mistyped standard is not a valid check, so if you find one of those problems it is worth rerunning the check properly and noting the date, rather than leaving the earlier printout as your record.

When to call us

• The check fails with a confirmed stored value, fresh in-date gas, good flow, and a new mouthpiece. The instrument needs adjustment.
• You get an E-code at any point. That is a different problem and inhibits the instrument.
• The regulator delivers nothing with a cylinder you know has gas in it.
• You need cylinders, a regulator, or mouthpieces. Part numbers and handling notes are in our supplies guide.

Call the office at 513-891-0868 with the serial number, the standard value on your cylinder, the value the instrument had stored, and the exact result the check printed.