Err 03 means your softener is unable to determine the position of its internal valve. Nine times out of ten, this is caused by a faulty motor, a broken wire, or a microswitch that has failed to register the cam rotation.
Err 03 is almost always mechanical, not electronic. The motor tries to spin the valve during regeneration, but if the position switch doesn't click within a set timeframe, the board kills the cycle and throws this code to avoid wasting salt or flooding the brine tank. Check the wiring harness first. It's a $4 fix instead of a $40 one, and it's the cause way more often than people think.
Phillips #2 screwdriver, Small flathead screwdriver
What Does the Err 03 Code Mean?
Here's the deal with Err 03: your softener can't figure out where its valve is sitting. It doesn't know if it's in service mode, backwash, or rinse. I usually find a cracked plastic cam or a burned-out motor, but honestly, half the time it's just a corroded connector on the wiring harness. Pretty common on units that are 5-8 years old, especially if they're sitting in a garage or basement that gets humid in the summer.
Most Likely Causes
Based on aggregated repair data, here is the probability breakdown for this error code:
Microswitch Failure45%
Motor Burnout30%
Wiring Issues15%
Mechanical Jam10%
Symptoms You May Notice
Your tap water feels flat and leaves scale rings in the sink within a day or two, meaning you're running on untreated hard water and the softener stopped doing its job entirely.
The display is locked on Err 03 and won't budge no matter what buttons you press or how long you hold them.
Salt level in the brine tank hasn't dropped in weeks, which means no regeneration cycles are completing and the resin bed is exhausted.
You can actually hear the motor humming for a few seconds when a cycle tries to start, but nothing moves and then the error code comes back up.
Scale is building up on your faucet aerators and showerheads way faster than normal, and your water heater is probably working harder than it used to.
Can you reset a Kenmore waterheater to clear the Err 03 code?
Unplug the power transformer from the wall outlet, not just from the back of the unit. Wait a full 60 seconds so the board completely loses power and clears its memory. Plug it back in. The display should flash all segments briefly, then return to the current time. Hold the Regen button for 3 seconds to manually advance the valve one position and watch if the motor moves. If it does and the code clears, you're good. If Err 03 comes right back, the fault is still present.
Tools Required for Diagnosis
Phillips #2 screwdriverSmall flathead screwdriverNeedle nose pliersDigital multimeter with AC voltage and continuity modesSmall wire brush for cleaning corroded terminalsFlashlight or headlamp
Diagnostic Checklist
Follow these steps in order. We start with the easiest external fixes before opening up the machine.
ComponentComponent Under Test
Expected Range110–125 VAC
ConditionIf Open (OL) or infinite, replace component.
Frequently Asked Questions
Can I still use my water while Err 03 is displayed?
Yeah, water's still flowing through the house, it just isn't being softened. The unit's stuck in whatever position it was in when the error hit. If it stopped mid-backwash you might get a small burst of discolored water for a minute, but it won't hurt anything. Just know that hard water deposits are going to show up fast, especially on your faucet aerators and in your water heater. Tankless heaters in particular hate hard water, so don't let this sit more than a week or two.
How do I reset the Kenmore softener after fixing the motor?
Pull the wall plug for a full 60 seconds, don't just flip the breaker. You want the control board to fully lose power and reset its cycle state. Plug it back in, hold the Regen button to manually advance the valve, and watch if it moves cleanly through a position. If Err 03 comes back immediately, something in the switch signal chain is still broken. Reseating connectors one more time before calling it a board issue is worth doing.
Why did my motor fail after only a few years?
High iron content is basically motor poison on these. I replaced three drive motors last month on units that were under 5 years old, all in the same subdivision with high-iron well water. The iron makes the valve seals gummy over time, and the motor strains against that extra resistance every single regeneration cycle until it burns out. If your water tests above 1-2 ppm iron, put an iron filter upstream of the softener. It protects the motor, the resin bed, and cuts your salt use too.
Is the microswitch sold separately from the motor?
Yes, and it's usually $8-15 depending on the model. Always check this before buying a motor. If your motor sounds like it's running but the error persists, the switch is almost certainly the problem. Pull your model number from the label inside the cabinet door and search it with 'microswitch' or 'position switch' to find the right part. WS15X10015 fits a bunch of Kenmore units but confirm yours before ordering.
What if the motor turns but I still see Err 03?
That's a classic bad switch or cracked cam. The board doesn't care if the motor spins. It cares about the signal from the position switch telling it the valve actually moved to the right spot. If the cam isn't hitting that switch lever, or the switch can't send the signal, the board assumes nothing moved and throws the code again. Swap the switch first since it's cheap. If that doesn't fix it, look really closely at the cam for a hairline crack. Those are easy to miss until you flex it slightly with your fingers.
How long does this repair usually take?
Honestly, an hour tops if it's the switch or wiring. I've knocked out Err 03 calls in 20 minutes when it was just a loose connector. Motor replacement is maybe 45 minutes once you have the part. The control head on these Kenmore units is pretty accessible, nothing buried deep. The annoying part is usually waiting for the part to arrive if you're ordering online, so check if a local appliance parts store has it in stock.
Models Known to Experience Err 03 Errors
This repair applies to most Kenmore waterheaters with this error code. Common model numbers include: