Shimadzu HPLC Troubleshooting: Common Error Messages and Fixes — Analytical Instrument Guide
The error messages we meet most often on Shimadzu LC-2010 and LC-2010C HT systems, what each one usually means on the bench, and what to check before you call an engineer.
A message on the screen is a symptom, not a diagnosis. The same error can come from a part that costs very little or from a main board, and the job is to rule out the cheap causes first. This is how we work through the messages we meet most often on Shimadzu HPLC systems, mainly the LC-2010 and LC-2010C HT integrated systems that we service regularly.
The exact wording differs between models and firmware versions. Write the message down exactly as it appears, and photograph the screen, before you clear it.
Quick reference
| Message or symptom | What it usually means | Check first |
|---|---|---|
| "No pump home" | The pump's position sensor did not register the drive turning | Disc centred in the U-shaped sensor, then the sensor, the pump drive board, the main board |
| Autosampler metering pump does not return home | The measuring pump plunger did not reach its home position | Whether it fails only at larger volumes, then the power supply under load |
| "COOLING FAN: PUMP" with the fan running | The fan-detection circuit, not the fan | Fan type (three wires), then the detection line on the connector board |
| High pressure | A blockage in the flow path | Line filter, guard column, column |
| Pressure fluctuating | Air, a check valve or a pump seal | Degas and purge, then check valves, then seals |
| Pressure falling, poor peak areas | A leak, often at the autosampler needle seal | Needle seal, fittings, pump head |
| Low lamp energy, noisy baseline | A detector lamp near the end of its life, or a dirty flow cell | Lamp hours and energy test, then the flow cell |
| No display at power-on | The power supply | Whether the fans run at switch-on |
"No pump home"
This error comes from the pump's own position sensing. Behind the left side panel of the pump section on the LC-2010 there is a black disc with a cut-out, turning between the arms of a U-shaped optical sensor. Each time the cut-out passes, the sensor counts it, and the instrument uses those counts to check that the pump is turning as it should. When the count doesn't arrive, you get "no pump home".
Check in this order:
- Is the disc rubbing the sensor? It must pass exactly through the centre of the gap. A rubbing disc can damage the sensor or slowly coat its light path.
- Is the sensor dead? If the disc turns cleanly and centred and there is still no count, suspect the sensor.
- Is the pump drive board passing the signal on? The sensor can count correctly while the signal never reaches the main board.
- Is it the main board? In our experience, once the mechanism, the sensor, the wiring and the drive board check out, most pump errors on this instrument end at the main board. A failed component there can stop the pump turning at all, and then the sensor never counts.
The full pump walkthrough, including high pressure and air, is in our LC-2010C HT pump troubleshooting guide.
Autosampler: the metering pump does not return home
On the LC-2010C HT autosampler, a "no home" error on the metering (measuring) pump means its plunger didn't get back to its reference position. The first sign can be poor repeatability, with peak area RSD out of limit, before the error appears at all.
In one case the autosampler injected 40 µL without trouble but failed every time at 50 µL. The plunger travelled back further than normal and stalled before it could return home, and a rod sensor error appeared alongside. 50 µL is well inside the injection range, so this wasn't a volume limit.
Swapping parts told us more than any single reading. The main board, the autosampler board and the complete injector assembly were each changed, and each one worked perfectly in our workshop. At the customer's site every one of them failed, including an injector assembly taken from a second instrument. The fault was therefore not in any part that travelled. That left the site's mains supply and the instrument's own power supply, which stayed on site, as the suspects.
The lesson: when an error follows the site and not the part, measure the supply during the failing injection before buying boards.
"COOLING FAN: PUMP" while the fan is spinning
A fatal "COOLING FAN: PUMP" error locks the pump out completely, and pressing CE only clears it for a few seconds. The obvious move is to replace the fan. On an LC-2010 we traced exactly this error, with the fan running at full speed, to one shorted fan-detection transistor on the LC2K-CNCT connector board. The fan was fine; the signal that reports it wasn't. Replacing that single component cleared the error, with no new fan and no new board.
For the engineer, two quick checks come first. Count the fan wires: a two-wire fan has no detection output at all, and fitting one in place of a three-wire fan produces this error by itself. Then measure the fan supply and the detection line. In the lab, just note the error and check that the vents are not blocked; the checks inside the instrument are a job for an engineer. The full measurements are in the cooling fan case study.
Pressure errors: high, low or fluctuating
Pressure messages are the most common of all, and most of them aren't electronic faults.
- High pressure: something in the flow path has narrowed. Start with the line filter, which is cheap and quick to change, then the guard column and the column. A phosphate buffer flushed straight to organic solvent crystallises and can block the pump, the injector and the column together, so always go buffer, then water, then organic.
- Fluctuating pressure: think check valve, line filter, pump seal, in that order. Air gives the same picture: if purging doesn't clear the line, degas the mobile phase and purge again before suspecting the hardware.
- Falling pressure: look for a leak. On an LC-2010 CHT we found a worn PEEK needle seal in the autosampler leaking at every injection. The pressure dropped and fluctuated, peak areas fell sharply, and the baseline and retention times became unstable. A new needle seal fixed it.
Low lamp energy and a noisy baseline
A low lamp energy message together with a noisy or drifting baseline usually means a deuterium lamp near the end of its life, at around 2,000 hours of use. Check the lamp hours and run the energy test before ordering a lamp, because a dirty flow cell or air in the cell gives the same symptom and costs nothing to fix. Our baseline noise and drift guide covers the other causes.
No display at power-on
On one Shimadzu HPLC that would not power on and showed no display, the cause was the power supply. Its cooling fan had stopped, the power supply board overheated, and the unit would not come up. A new power supply board and fan brought the display back, and the repeatability check afterwards was fine.
If a module goes dead, listen for its fans at switch-on and tell us what you hear. Do not open the power supply yourself: it carries mains voltage.
Before you call
- Photograph the screen and write down the exact message.
- Note the model, the module and the serial number.
- Note when it started and what changed just before: a new mobile phase, a power cut, a move.
- Try only the safe checks: line filter, degas and purge, lamp hours.
- Do not keep clearing a fatal error and restarting; note it and stop.
If the safe checks don't clear it, the fault is usually a sensor, a board or the power supply, and it needs an engineer with the parts and a meter. Spare parts such as pump seal kits, check valve cartridges and deuterium lamps can be quoted for your model.
We service Shimadzu HPLC systems for laboratories in Thane, Ambernath, Navi Mumbai, Mumbai and Pune.
Shimadzu and the model names are used only to identify instruments. Vision Analytical is an independent service company and is not affiliated with Shimadzu Corporation.