The Kohler 400REZXD is a 400-kilowatt LPG industrial standby generator in an enclosed configuration. Rated at 295-400 kW standby depending on voltage, it uses a PSI/Doosan engine paired with a brushless permanent-magnet pilot exciter alternator at 1800 RPM. This unit is EPA certified for both stationary and mobile emergency and non-emergency applications, with hurricane-rated enclosure options featuring 186 mph wind load rating.
At 400 kW, gaseous generators offer a viable alternative to diesel for facilities that want to avoid fuel storage and SPCC compliance. LPG provides clean combustion with lower emissions, but at this power level propane consumption is high. Tank sizing, delivery contracts, and fuel availability during regional emergencies are critical planning factors. Facilities with reliable propane infrastructure benefit from the lower maintenance burden compared to diesel at this scale.
OnPoint Generators provides installation, maintenance, and emergency service for Kohler gaseous generators throughout Northern California. The PSI/Doosan engine platform in the 400 kW class is purpose-built for heavy commercial duty, and we structure PM programs around annual ignition, fuel system, and coolant inspections with attention to the pilot exciter alternator and higher-capacity fuel delivery components.
Tell us about the application — kW, voltage, application, install timeline — and we'll respond within one business day with budgetary pricing, lead time, and any sizing notes.
Manufacturer-recommended intervals for the Kohler 400REZXD under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 250 hours or 12 months
Coolant change
Every 3000 hours
Air filter
Every 500 hours
Spark plugs
Every 500 hours
Major overhaul
≈ 8,000 hours
Load bank test
Every 12 months
Common failure modes
What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.
Component
Symptom
Typical hours
Severity
Spark plugs / ignition
Misfire under load, cylinder dropout codes, rough idle
500+
minor
Turbocharger seals
Oil in intake, blue smoke, boost pressure loss
10,000+
moderate
Fuel pressure regulator / vaporizer
Hard starting, gas pressure fault, erratic idle
8,000+
moderate
Battery (starting)
Slow crank, failed exercise
8,760+
minor
Frequently Asked Questions
What is the standby rating of the Kohler 400REZXD?
The 400REZXD is rated 295-400 kW standby (369-500 kVA) depending on voltage configuration, with prime ratings of 360-365 kW, operating on LPG at 60 Hz.
What fuel does the Kohler 400REZXD use?
The 400REZXD operates on LPG (propane). Natural gas and dual-fuel variants are also available in the REZX line.
What is the difference between RZX and REZX models?
RZX designates the open-frame (skid-mounted) configuration, while REZX is the enclosed (sound-attenuated or weather-protective) version. Both use the same engine-alternator package; the difference is the enclosure.
400 kW gaseous-fueled commercial standby generator. Kohler/Rehlko 400REZXB — the flagship of Kohler's industrial gaseous lineup for large facilities and paralleling arrays. Note: the 400 kW Kohler gas genset is sold as the 400REZXB, not as 'KG400'.
