What does the Bosch dishwasher E02 / E0103 error code mean?

E02 (shown as E0103 on newer connected models) indicates a heater relay fault on the dishwasher's main control board. On some models the same code is triggered by a faulty temperature sensor or thermistor feeding incorrect readings to the relay, rather than the relay itself.

Can I fix a Bosch dishwasher E02 / E0103 error myself?

A breaker reset is worth trying first. If the code returns, diagnosis requires testing the relay and temperature sensor with a multimeter to identify which component failed. Replacing a relay on the control board or swapping the control board itself is not a typical DIY repair.

Is E02 the same problem on every Bosch dishwasher model?

Not always. Most models point to a heater relay fault on the main control board, but some models trigger E02 from a faulty temperature sensor or thermistor instead. A technician identifies the exact component before recommending a part.

How much does it cost to fix a Bosch dishwasher E02 / E0103 error?

If the issue is a faulty temperature sensor or thermistor, replacement typically costs $120–$220 in the Boston area, parts and labor included. If the main control board needs replacement, cost runs $220–$450 depending on model series.

Is it safe to keep using the dishwasher with an E02 error?

No. A heater relay fault can leave the heating element stuck on or unable to turn on at all, affecting both cycle performance and safety. Stop running cycles and book a diagnostic if the code persists after a breaker reset.

E02
E0103

Bosch · Dishwasher · Error Code

Bosch Dishwasher E02 / E0103 Error Code — Heater Relay Fault on Control Board

Technician Recommended Also shown as: E 02 E:02 E0103

Quick Answer

The E02 / E0103 error code means the main control board has detected a fault in its heater relay — the internal switch responsible for sending power to the wash water heating circuit. A breaker reset is always the first step and can clear temporary relay faults caused by power events. If the code returns, the most actionable DIY check is testing the NTC thermistor (temperature sensor) with a multimeter — a failed sensor can trick the board into raising E02 even when the relay itself is fine. A confirmed relay or control board fault requires a qualified technician, as Bosch-programmed power modules are not freely available for self-installation.

Time

10 min–2 hrs

Difficulty

Hard

Tools

Multimeter, Torx set

DIY Cost

$0–$60

What the E02 / E0103 Code Means

Inside your Bosch dishwasher's main control board sits a relay — an electrically operated switch — whose job is to route mains power to the heating element or heat pump that warms the wash water. E02 (displayed as E0103 on newer four-digit models) fires when the control board's own self-diagnostic routine detects that this heater relay is not operating correctly. The relay may be stuck open (failing to pass power to the heater), stuck closed (passing power when it shouldn't), or the board may be receiving feedback from the temperature sensor that doesn't match expected values, causing it to flag the relay circuit as faulty.

The practical symptoms are similar to E09 — water that doesn't heat up, dishes that come out cold or wet, and cycles that may halt partway through or complete without any heating occurring. The key difference is where the fault lives: E09 typically points to the heating element itself, while E02 specifically points to the relay circuit on the control board or the thermistor feeding it information.

Like E01/E0100, Bosch groups E02 and E0103 in the same family of power module faults — E01 through E05 on older displays all indicate a power module issue, with E02 being specifically the heater relay within that module. Bosch's own guidance for E0103 is a breaker reset followed by a call to customer support if the code persists, because power module repairs require a factory-trained technician on most current models.

Common Causes — Most Likely First

Temporary control board fault from a power event. A power outage, voltage spike, or tripped breaker mid-cycle can leave the heater relay's logic register in an error state, generating E02 without any component having actually failed. A breaker reset clears this. Common

Faulty NTC thermistor (temperature sensor). The thermistor feeds temperature data to the control board. If it reports an out-of-range reading — or no reading at all — the board cannot confirm the heater relay is working as expected and raises E02, even when the relay is physically fine. A failed thermistor reads "OL" (open line) on a multimeter. Common

Heater relay fault on the main control board. The relay itself has failed — either burned contacts that no longer close, or a relay that stays permanently closed. In both cases the board detects unexpected behavior in the heater circuit and raises E02. Occasional

Loose or damaged wiring between the control board and heating element. A wiring harness connector that has worked loose, corroded, or been chafed through breaks the feedback loop between the heater and the board, producing E02 without either component being defective. Occasional

Failed heating element or heat pump (secondary trigger). A completely open-circuited heater will produce no temperature rise at all, causing the board to flag the heater relay circuit as faulty. In this scenario E02 and E09 can appear together or alternately. Occasional

Failed main control board / power module. The power module itself has suffered internal damage beyond just the relay — a broader board failure. Replacement requires a factory-programmed unit and a certified technician on most Bosch models. Less common — needs technician

How to Fix the E02 / E0103 Error — Step by Step

Reset the circuit breaker for at least 5 minutes

Trip the dishwasher's breaker and leave it off for a full 5 minutes. This is Bosch's published first step for E0103 and is enough to clear a transient heater relay fault caused by a power event. A 30-second flip is often not long enough — the control board needs time to fully discharge.

Run a full test cycle and observe heating

Restore power and run a standard wash cycle. After 10–15 minutes, carefully open the door a crack (on a paused cycle where safe) and feel whether steam or heat is present in the tub. If the cycle completes with warm, dry dishes and no E02, the fault was a temporary board issue. Monitor for recurrence over the next few washes.

If E02 returns on the next cycle, the fault is hardware-based. Continue with the steps below.

Test the NTC thermistor with a multimeter

This is the most productive DIY check for a persistent E02. With the dishwasher fully disconnected from power, locate the NTC thermistor — a small two-wire sensor clipped to the sump or circulation pump housing. Disconnect it and set your multimeter to the ohms (Ω) setting. Touch the probes to the two terminals. A healthy thermistor reads a finite resistance at room temperature (consult your model's tech sheet for the exact value — typically 5–15 kΩ at 20°C). A reading of "OL" (open line / infinite resistance) means the thermistor has failed and needs replacement.

Tip: A replacement NTC thermistor is one of the cheapest parts on a Bosch dishwasher — typically $15–$40 — and replacing it yourself is straightforward if the multimeter test confirms it has failed.

Inspect wiring between the control board and heater

With power disconnected, trace the two larger wires from the control board down to the heating element or heat pump assembly. Check that all connectors are firmly seated and that the wire insulation shows no signs of melting, chafing, or corrosion at the terminals. Reseat any loose plugs and look closely at the board-side connectors for discoloration that would indicate heat damage.

Safety note: These wires carry mains voltage during normal operation. Only inspect them with the power fully disconnected at the breaker and the plug pulled from the wall.

Test the heating element for continuity

If the thermistor and wiring both check out, the heating element may itself have failed, causing the board to flag the relay circuit. With power off, disconnect the heater terminals and test continuity across them with a multimeter. An open circuit (no continuity) confirms a failed element — this is more of an E09 scenario but can surface as E02 on some models.

Book a technician for control board diagnosis

If the thermistor is good, wiring is intact, the element tests fine, and E02 still returns — the heater relay on the control board itself has failed. Relay replacement at the component level requires specialist skills and equipment, and Bosch's power module programming restrictions mean a full board swap must be done by a factory-trained engineer on most current models. This is the point to call a technician.

When to Call a Technician

A breaker reset and thermistor test are the realistic DIY options for E02/E0103. Book a professional repair if:

E02 or E0103 returns after a full 5-minute breaker reset and test cycle
Dishes consistently come out cold and wet with no heat during the cycle
The thermistor tests good (normal ohm reading) but the code persists
Wiring inspection shows no obvious fault but E02 keeps returning
The heating element also tests open — confirming a heater failure that needs replacement
The control board relay or power module needs replacement — factory-programmed units are not available for self-installation on most Bosch models

Repair Cost Expectations

If You Fix It Yourself

$0–$60

A breaker reset costs nothing. A replacement NTC thermistor runs $15–$40 as a DIY part and is the most affordable fix when the thermistor is the confirmed cause.

Professional Repair

$200–$500

Typical range in the Boston area for control board relay diagnosis plus thermistor, heating element, or full board replacement — parts and labor included. Board replacement trends toward the higher end.

Still Getting E02 or E0103? We'll Fix Your Bosch Dishwasher.

Same-day appointments across Boston. Certified Bosch technicians, common parts stocked on the truck, and a 90-day warranty on every repair.

Book Bosch Dishwasher Repair Call (781) 666-9565

Frequently Asked Questions

Are E02 and E0103 the same error?

Yes — they describe the same fault on different Bosch display generations. E02 is shown on older two-digit displays and indicates a heater relay fault or thermistor issue on the main control board. E0103 is the four-digit equivalent on newer HomeConnect and Series 8 models. The diagnosis and repair path is identical for both.

What is the difference between E02 and E01 on a Bosch dishwasher?

Both codes point to faults in the heating circuit at the main control board, and both belong to the same E01–E05 power module fault family. The distinction is that E01 specifically flags the heat pump motor circuit — the motor that circulates and heats water — while E02 flags the heater relay — the switch inside the board that routes power to the heating element. In practice, a failed thermistor can trigger either code, so the thermistor test is a useful first step for both.

Can a bad thermistor really cause E02?

Yes, and it's one of the more common reasons E02 appears on machines where the control board relay itself is actually fine. The board uses the thermistor's temperature readings to verify that the heater relay is working — if the sensor reports no temperature rise (because it has failed open), the board concludes the relay isn't doing its job and raises E02. Replacing the thermistor is a relatively cheap and straightforward fix when this is confirmed.

Can I replace the control board myself to fix E02?

On most current Bosch models, replacement power modules are factory-programmed with unit-specific configuration data. Installing an unprogrammed board will result in a non-functional dishwasher. Bosch recommends a factory-certified technician for any power module or control board replacement. Before reaching that point, it's worth confirming the thermistor is the actual culprit — a much less expensive repair that a confident DIYer can handle.

How much does it cost to fix an E02 or E0103 error?

A breaker reset costs nothing. A replacement NTC thermistor as a DIY part typically runs $15–$40. Professional repair in the Boston area for control board relay diagnosis plus thermistor, heating element, or full board replacement typically runs $200–$500, parts and labor included, with control board jobs toward the higher end of that range.