Troubleshooting guide.
Alarms, no output, over-temperature and water-quality faults — symptom, likely cause and the action to take.
What are the most common faults on a PEM hydrogen enhancement unit?
Most support cases resolve to water quality or the vibration sensor. Water outside TDS ≤ 5 µS/cm — or an overdue resin filter — trips the high-TDS alarm and reduces output; a mis-set or loose vibration sensor causes a unit that never starts or that runs with the engine off. Power supply, water level and mounting location cover almost everything else.
- Water quality first: purified water, TDS ≤ 5 µS/cm, resin filter every 6–9 months
- No output: check DC supply and fuse, then water level, then vibration sensor
- Runs with engine off: reduce vibration-sensor sensitivity, remount the sensor
- Over-temperature: relocate away from exhaust heat, improve ventilation
- Low output: replace resin filter before suspecting the stack
- Water spec
- TDS ≤ 5 µS/cm
- Filter interval
- 6 – 9 months
- Supply
- 12 / 24 V DC
- Support
- Remote, business hours
Symptom → cause → action.
| Symptom | Likely cause | Action |
|---|---|---|
| Water-shortage alarm | Reservoir below minimum level | Refill with purified water (TDS ≤ 5 µS/cm). Check for leaks at fittings and hose clamps. |
| High-TDS alarm | Out-of-spec water or exhausted resin filter | Drain, fit a new resin filter, refill with purified or deionized water. Do not use tap, rain, bore or mineral water. |
| No gas output, engine running | Power supply, water level or vibration sensor | Check fuse and DC supply at the battery, confirm water level, then adjust vibration-sensor sensitivity and confirm the sensor is firmly mounted. |
| Unit runs with engine off | Vibration sensor set too sensitive or picking up external movement | Reduce sensitivity and relocate the sensor away from body panels that move independently of the engine. |
| Over-temperature shutdown | Mounting location, airflow or ambient heat | Relocate away from exhaust and turbo heat, provide ventilation, and confirm ambient conditions are within the operating window. |
| Output lower than commissioning | Overdue resin filter, conductivity drift, or intake leak | Replace the resin filter, refill with purified water, then pressure-check intake plumbing and one-way valve. |
| Fuel data shows no change | Trial method rather than hardware | Confirm a controlled baseline exists and duty cycle, drivers and fuel supplier were held constant. |
If it is still not resolved.
Send the unit model and serial, the alarm shown, DC supply voltage measured at the unit, water source and last filter change date, and a photo of the mounting location and intake connection. That set is usually enough to close a case remotely.
See also the installation guide, full FAQ and replacement resin filters.
Questions.
The high-TDS alarm is on. What do I do?
- Stop using the current water. Drain the reservoir, fit a fresh resin filter and refill with purified or deionized water at TDS ≤ 5 µS/cm. The alarm should clear once conductivity is back in spec. Repeat trips usually mean the water source is out of spec rather than a fault.
The unit produces no gas. Where do I start?
- Check three things in order: supply voltage and fuse at the battery, water level in the reservoir, and vibration-sensor pick-up. A unit that never starts while the engine runs is most often a sensitivity setting or a loose sensor mount.
Output seems lower than when it was new.
- The usual cause is water quality: an overdue resin filter lets conductivity drift and reduces stack performance. Replace the filter, refill with purified water, and confirm intake-line integrity before assuming a stack issue.
How often should the resin filter be replaced?
- Every 6–9 months under normal duty, or sooner if the high-TDS alarm trips. Filters are compatible with the HHO-450, HHO-675 and HHO-900 units.
The over-temperature shutdown keeps triggering.
- Review mounting location: airflow, distance from exhaust or turbo heat, and ambient temperature. Units mounted in an enclosed, unventilated space or against a hot surface will cycle on temperature.
Continue reading.
Hydrogen combustion enhancement
What it is, how PEM gas reaches the cylinder, and what it does not do.
Engine performance improvement
Flame speed, burn completeness and load response on diesel engines.
Fuel efficiency
How to baseline and measure litres per 100 km or litres per hour.
Emissions reduction
Soot, particulate and unburnt-fuel behaviour, and how to test it.
Installation guide
Nine-step fitting sequence: mounting, wiring, gas line, commissioning.
Safety & compliance
On-demand gas, no storage, alarms, shutdowns and reversibility.
Case studies & field results
Published operator data and trial methodology.
Compare PEM systems
A-450 to D-900 side by side: displacement, output, current draw.
FAQ
Answers on fitment, water, warranty, freight and duty cycles.