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Bosch H01 Code: Water Taking Too Long to Heat

Quick Answer

H01 is a timeout code, not an outright failure. Your Bosch waited for the water to reach the target temperature and gave up. The most common cause is incoming water being too cold - if your home water heater is set below 120F or is far from the kitchen, the dishwasher starts with cold water and cannot heat it fast enough.

H01 is a timeout code, not an outright failure. Your Bosch waited for the water to reach the target temperature and gave up. The most common cause is incoming water being too cold - if your home water heater is set below 120F or is far from the kitchen, the dishwasher starts with cold water and cannot heat it fast enough. Running the hot water tap for 60 seconds before starting the dishwasher often clears H01 permanently. If H01 persists with hot incoming water, the NTC sensor or flow-through heater needs testing.

BoschDishwasherSeverity: moderateDifficulty: intermediate85% DIY Success
Time to Fix
15–90 min
Difficulty
intermediate
Parts Cost
$15 – $160
Tools Needed
Multimeter, Flathead screwdriver
Wrong code?

Not seeing H01 on your display?

Select what your appliance is actually doing and we'll take you to the right guide.

flow-through heater complete failure
E09
NTC thermistor reading out of range
E11
poor wash quality from blocked filter
E22
water temperature not reached within time limit
MieleF52

What Does the H01 Code Mean?

H01 differs from E09 in that E09 means the heater has completely failed, while H01 means the heater is working but could not raise the water temperature to target within the time limit. Bosch dishwashers have a built-in maximum heat-up time. If the temperature rise is too slow - due to cold incoming water, a partially degraded heater, or a drifting NTC sensor - the controller throws H01 and stops the cycle rather than running indefinitely.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Incoming water temperature below 120F (most common)40%
NTC temperature sensor drift reading water as colder than it is24%
Partially degraded flow-through heater with reduced output14%
Cold weather reducing pipe temperature in exterior walls12%
Long distance between water heater and kitchen causing cold water on startup10%

Symptoms You May Notice

  • H01 displayed after several minutes of wash cycle
  • Cycle stops at wash or sanitize phase
  • Dishes not fully cleaned or sanitized
  • H01 appearing only during cold weather months

Can you reset a Bosch dishwasher to clear the H01 code?

Hold Start/Reset for 3-5 seconds to clear H01. Then pre-run hot water for 60 seconds and restart the cycle.

Tools Required for Diagnosis

MultimeterFlathead screwdriver

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Pre-run hot water and test again

At the kitchen sink, run the hot water for 60 full seconds until the water is as hot as it gets. Then immediately start the dishwasher without any delay. This ensures hot water is already in the supply line when the fill valve opens. Run a Normal or Heavy cycle and observe if H01 appears.

2

Check home water heater setting

3

Test the NTC sensor

ComponentComponent Under Test
Expected Range10000–12000 ohms at 70F
ConditionIf Open (OL) or infinite, replace component.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name
NTC Temperature Sensor00165258 · $15–$30
Flow-Through Heater Assembly00674541 · $85–$160

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs
Labor Approach
Our Verdict
REPAIR
Estimated Cost: $88 (Parts) vs $650 (New Machine)

Frequently Asked Questions

Is H01 the same as E09 on a Bosch dishwasher?
No. H01 is a timeout - the heater ran but water did not reach the target temperature fast enough. E09 means the heater has completely failed and is producing no heat at all. If pre-running your hot water tap for 60 seconds makes H01 disappear, the heater is fine. If E09 appears, the heater has failed and needs to be replaced.
Should I run the hot water tap before starting my Bosch dishwasher?
Yes, especially in homes where the water heater is more than 20 feet from the kitchen. Running the tap for 60 seconds flushes the cold water sitting in the supply line and ensures the dishwasher fills with hot water from the start. This simple habit eliminates H01 in the majority of cases where no hardware failure is involved.
What temperature does a Bosch dishwasher need to operate properly?
Bosch recommends an incoming hot water supply of 120-140F (49-60C). The main wash cycle targets 120-140F depending on the cycle selected. The sanitize cycle on compatible models reaches 155F (68C). If your water heater is set below 120F, the dishwasher will struggle to hit its targets within the allotted heat-up window.
Can cold weather cause H01?
Yes. In homes with supply pipes running through exterior walls or unheated crawl spaces, water sitting in the pipes during winter can be significantly colder than the water heater's set temperature. The dishwasher then has to heat this cold water up by 30-40F instead of 5-10F, which can exceed the heat-up time limit. Insulating exposed pipes is the permanent fix in these cases.
Why does H01 only appear during winter months?
Cold ambient temperatures reduce pipe water temperature between the water heater and the dishwasher. In summer, the water sitting in pipes may be 65-70F. In winter, it can drop to 45-55F. This larger temperature difference at the start of the cycle requires more heating time. If your dishwasher only shows H01 from November through March, cold supply pipes are almost certainly the cause.

Related Bosch Dishwasher Error Codes

Code: E09Bosch E09: Heating Element Not WorkingCode: E11Bosch E11 Error: Temperature Sensor (NTC) FaultCode: E22Bosch E22 Error: Filter Blocked

Same Fix on Other Brands

Miele dishwasherF52: Miele Dishwasher F52: Heating Timeout

Same Fix Works on These Brands

Bosch shares the same hardware platform with these brands. The diagnosis and repair steps are identical.

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Models Known to Experience H01 Errors

This repair applies to most Bosch dishwashers with this error code. Common model numbers include:

SHPM88Z75N, SHPM88Z55N, SHPK7ZL55N, SHE3AR75UC, SHEM63W55N, SHPM65Z55N, SHE3AR72UC, SHDF78Z55N, SHEM78ZH5N, SHPM98Z75N

Last verified for technical accuracy on March 14, 2026