The 30-second answer: Kohler generators are mostly standby home units, so the failures skew electrical and control-board related rather than carburetor problems. Won’t auto-start on outage: check the starting battery under load first, it’s the most common cause by far. RDC2/RXT controller shows a fault: read the exact wording on the display before opening anything. Runs during exercise but not a real outage: usually battery or fuel supply, not a real fault — see our guide on standby generators that won’t start during an outage.
Kohler’s residential lineup is almost entirely standby generators tied to natural gas or propane, so the common problems look different from a portable — less carburetor, more battery, controller, and transfer switch.
Won’t auto-start when the power actually goes out
By far the most common Kohler standby complaint: the unit passes its scheduled exercise cycle every week without issue, then fails to start during a real outage. This is almost always the starting battery — it holds enough charge for a short, light exercise run but can’t deliver under a real cold start. Test battery voltage under cranking load, not just resting voltage, since a trickle charger can mask a weak battery for months.
RDC2 or RXT controller showing a fault
Kohler’s RDC2 and older RXT controllers display plain-language fault text rather than cryptic codes — things like a sensing or charging fault spelled out on the screen. Always read the exact wording before doing anything else; it tells you whether the issue is on the battery/charging side, the transfer side, or the engine side, which changes where you look next.
Transfer switch won’t engage
If the generator itself runs fine but the house doesn’t get power, the issue is in the automatic transfer switch, not the generator — see our full transfer switch troubleshooting guide for the ATS-specific diagnostic path.
Won’t start on propane/natural gas after storage
Less common on gas-fed standby units than on gasoline portables, but a propane regulator that’s been sitting can still cause hard starting — confirm the tank valve is fully open (not just cracked) and that the regulator hasn’t developed a restriction. For natural gas units, gas pressure at the meter is worth checking if the issue only shows up during high-demand periods.