E4 F8 Error Code on Dishwasher: What It Means & How to Fix It

If your dishwasher flashes E4 F8, it’s telling you the water isn’t heating fast enough or at all. On most LG and some Kenmore models, this code tracks the temperature rise during the wash and dry cycles. A failed heating element or a bad thermistor (temperature sensor) causes the vast majority of these errors. Start with a simple reset, then go straight to the continuity checks — no need to guess.

Start With a Reset

A glitchy control board can throw a false E4 F8. Rule that out first so you’re not chasing parts you don’t need.

1. Unplug the dishwasher from the wall or flip the breaker off.

2. Wait a full 5 minutes. Residual voltage needs to drain from the control board capacitors.

3. Plug it back in and run a short wash cycle with heat dry turned on.

What happens next tells you where to go: If the error clears and the water feels warm against the door glass halfway through the cycle, you had a temporary hiccup — you’re done. If E4 F8 comes back immediately (within the first few minutes), the problem is almost certainly the heating element or thermistor. If the code returns 10–15 minutes into the cycle, the element may be heating weakly or your incoming water is too cold, and you should check the water heater temperature at the tap before replacing anything.

Verification: Wait until the dishwasher is about 15 minutes into the cycle, then open the door carefully (watch for steam) and feel the water pooled at the bottom. It should be noticeably warm — at least 100°F. If it’s cold, the element isn’t working.

What to Check Before Buying Parts

The table below covers the five most common troublemakers. Run through these checks in order. Multimeter is required for items 3 and 4.

Check Point	What to Look For	Pass / Fail
Incoming water temperature	Measure hot water at the nearest faucet — should be at least 120°F	Under 110°F? Turn your water heater up first
Heating element (visual)	Burn marks, cracks, bulging, or rust on the element tube	Replace if any damage visible
Heating element (continuity)	Multimeter reading between 10 and 50 ohms across the terminals	OL (open) or 0 ohms = replace
Thermistor resistance	Multimeter reading between 10,000 and 50,000 ohms at room temp	Outside range or OL = replace
Wire harness and connectors	Melted plastic, corrosion, loose fit at element or sensor pins	Re-seat or replace harness

If your incoming water measures under 110°F, the heater has to work much harder to hit target temperature, which can trigger the error even with a perfectly good element. Fix the hot water supply first, then retest.

Testing the Parts That Actually Fail

You need a basic digital multimeter set to resistance (ohms, Ω). These two tests cover 80% of E4 F8 cases.

Thermistor test:

• Find the thermistor — a small plastic button clipped into the side of the tub, usually below the lower wash arm on the left or right.
• Unplug its wire connector.
• Measure across the two pins. At room temperature (68–77°F), a good thermistor reads 10kΩ to 50kΩ.
• An open reading (OL) or a short (near 0Ω) means the sensor is dead. Replace it.

Heating element test:

• The element is the oval or round metal tube at the bottom inside the tub.
• Disconnect the two wire leads from its terminals.
• Measure across the terminals. A working element reads 10 to 50Ω. An open reading (OL) means the internal coil is burned out.
• Next, check for a ground short: touch one probe to a terminal and the other to bare metal on the tub or chassis. Any reading at all (even a few ohms) means the element is shorted to ground — replace it immediately.

BLOCKQUOTE_0

That thermal fuse is built into the heating element assembly on most LG models. If the element passes the continuity test but the dishwasher still won’t heat, the internal thermal fuse may have blown. You can’t replace the fuse alone — swap the entire element assembly.

Branch point after testing: If the thermistor is out of range but the element tests good, replace just the thermistor and retest. If both test good, the fault is likely a wiring harness issue or a failed control board relay — skip ahead to the escalation section.

Replacing the Heating Element

Tools needed: screwdriver set, 1/4-inch nut driver or 7/16-inch socket, multimeter, safety gloves.

1. Kill power. Unplug the dishwasher or shut off the breaker.

2. Remove the lower spray arm and the mesh filter. Set them aside where you won’t lose the screws.

3. Take out the lower rack if it blocks access to the element.

4. Unplug the two wire leads from the heating element terminals. Snap a photo first so you know which wire goes where — polarity usually doesn’t matter here, but some models use different spade sizes.

5. Remove the center nut holding the element to the tub (typically 7/16-inch on LG models). Turn counterclockwise.

6. Pull the element straight out. If it sticks, mineral deposits have built up around the gasket — wiggle gently side to side. Do not pry against the tub edge.

7. Install the new element. Slide it in, make sure the rubber gasket sits evenly all around, and tighten the center nut hand-tight plus a quarter turn with the driver. Overtightening can crack the tub.

8. Reconnect the wire leads. Push each connector fully onto the terminal — it should click or feel snug.

9. Reassemble the filter, spray arm, and rack.

10. Run a test cycle with heat dry. Verify the fix by feeling the water temp mid-cycle (should be warm, 100°F or above) and confirming the error code stays off through the entire cycle.

Replacing the Thermistor

If the element passes its tests but the code persists, swap the thermistor. It’s a cheap part (typically under $15) and takes ten minutes.

1. Locate the thermistor — clipped into the side of the tub, below the wash arm.

2. Pry it loose gently with a small flathead screwdriver. It snaps into a plastic holder — don’t yank the wires.

3. Unplug the wire harness from the thermistor body.

4. Snap the new thermistor into the holder and plug the harness back in. Match the pin count — most LG units use a 2-pin connector.

5. Run a test cycle with heat dry. Verify the same way: feel for warm water mid-cycle and ensure the error doesn’t return.

What the Timing of the Error Tells You

When E4 F8 appears matters. Here’s how to read the clock:

• Error appears within 2 minutes of starting — The control board detected the heater is completely dead or the thermistor is open. Test both immediately. This is the most common failure mode.
• Error appears 10–20 minutes in — The water is heating, but not fast enough. The element may be partially burned out (high resistance) or your incoming water is too cold. Check the water heater first, then test element resistance.
• Error during the dry cycle only — The heater turns on for drying, but the sensor doesn’t register the temperature rise. Likely a failing thermistor that drifts out of spec when hot, or a loose connector that breaks contact when the tub vibrates.
• Intermittent error (comes and goes over several cycles) — Wiggle the wire harness at the element, thermistor, and control board connector while monitoring a multimeter. A change in resistance when you wiggle means a broken wire or corroded pin.

When the Fix Goes Beyond Parts

If both the element and thermistor test good and the reset didn’t help, you’re looking at three likely causes that take more effort to verify:

• Failed control board relay — The board sends voltage to the element through a soldered relay. If it’s stuck open or welded shut, the element never gets power. Listen for a distinct click sound during a heat cycle — no click means the relay isn’t switching. Board replacement typically runs $100–200 for the part alone.
• Broken wire in the main harness — A break inside the insulation between the board and the element. This requires tracing the circuit with a multimeter and continuity test, splicing the wire, or replacing the harness section.
• Failed main control board — The least common cause but the most expensive. If you’ve verified power at the board output during a heat call and nothing reaches the element, the board is bad.

Stop point: If your dishwasher is over 7 years old and you need a control board, price a replacement machine first. A new board plus labor often exceeds half the cost of a new dishwasher, and you’ll still have an aging pump, seals, and spray arms behind it.

FAQ: E4 F8 Error Code on Dishwasher

Q: Can low water pressure cause the E4 F8 error?

A: Not directly. Low pressure slows the fill but the error tracks temperature rise, not fill time. However, if the water level in the tub is too low (from a restricted fill valve or clogged inlet screen), the heating element can overheat and trip its internal thermal fuse, which then triggers the code. Check the fill valve screen first if the tub looks low during the cycle.

Q: How do I confirm the fix worked before running a full cycle?

A: After replacing the element or thermistor, run a short wash cycle with heat dry. Halfway through the wash, open the door carefully and touch the water at the bottom. It should feel warm (100–120°F). If the cycle completes without triggering the error and the dishes come out hot, the fix is confirmed.

Q: Do I need a special multimeter for dishwasher testing?

A: No. Any basic digital multimeter with a resistance (Ω) setting works. The ranges you’re checking — 10–50Ω for the element, 10k–50kΩ for the thermistor — are well within what a $20 meter can read. Spend your money on the parts, not the tool.

Q: Will the dishwasher run at all with this error?

A: On most LG models, E4 F8 stops the cycle and prevents further operation until the code is cleared. Some units will let you cancel and drain, but won’t start a new cycle until the underlying problem is fixed or the code is cleared by a reset.