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Error code reference

Bosch Dryer Error Code E:9024

Power supply

Bosch codesBosch dryer codes

Power supply - external impact (line sync error) (4-digit equivalent of E:40).

First step from the service manual

Check customers mains voltage and frequency.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E:9024 means on a Bosch dryer

Error code E:9024 on a Bosch dryer indicates a power supply issue caused by an external impact, specifically a line synchronization error. This code is the 4-digit equivalent of E:40 and means the dryer's control board is detecting an inconsistency or disruption in the incoming AC mains supply, either in voltage level, frequency stability, or both. The control electronics continuously monitor the incoming power line to synchronize internal timing and motor control operations, and when the signal deviates outside acceptable parameters, this fault is triggered.

The most common external causes include fluctuations from the utility grid, voltage sags or surges from other high-draw appliances on the same circuit, or unstable frequency delivery from a generator or non-standard power source. In homes where the mains voltage is borderline low or high, or where the 60 Hz (or 50 Hz, depending on region) frequency is inconsistent, the dryer's control board may repeatedly lose sync with the power line signal. This is an externally driven fault, meaning the dryer itself is not necessarily defective.

The first diagnostic step is to check the customer's mains voltage and frequency at the outlet or terminal block supplying the dryer. A true RMS multimeter should be used to verify that voltage is within the rated range and that no significant fluctuation is occurring under load. If the supply checks out as stable and within spec, the internal line sync detection circuit on the control board may itself be at fault.

Source: manufacturer service documentation.

Common causes of E:9024

  1. 01

    Unstable or out-of-spec mains voltage

    Wiring / connection

    Utility-supplied voltage that is too high, too low, or fluctuating outside the dryer's rated input range will trigger a line sync error. Check the outlet voltage with a true RMS multimeter while the dryer is running to detect sags or surges.

  2. 02

    Mains frequency instability

    Wiring / connection

    The dryer's control board monitors AC frequency to synchronize its operations. Power from a generator or a grid with unstable frequency can cause this fault even when voltage appears correct.

  3. 03

    Shared circuit load causing voltage sag

    Wiring / connection

    High-draw appliances on the same branch circuit, such as an air conditioner or electric range, can cause momentary voltage drops when they cycle on. This intermittently disrupts the dryer's line sync detection.

  4. 04

    Faulty outlet or wiring connection

    Wiring / connection

    A loose terminal at the wall outlet, a deteriorated cord connection, or a poor connection at the dryer's terminal block can introduce resistance and cause voltage instability. Inspect all connections for signs of arcing, heat damage, or looseness.

  5. 05

    Defective control board

    Part replacement

    If the mains supply has been confirmed stable and within spec, the line sync detection circuit on the main control board may itself be malfunctioning, causing a false fault. Board replacement would be required in this case.

See the test procedure for each cause

Frequently asked questions about E:9024

What does E:9024 mean on a Bosch dryer?
E:9024 is a power supply fault indicating a line synchronization error caused by an external impact to the mains supply. It is the 4-digit equivalent of error E:40. The dryer's control board has detected that the incoming AC voltage or frequency is outside acceptable parameters. This is typically an external issue related to the home's electrical supply rather than an internal dryer component failure.
How do I fix error E:9024 on my Bosch dryer?
Start by checking the mains voltage and frequency at the outlet or terminal block supplying the dryer using a true RMS multimeter. Look for voltage that is out of range or fluctuating, especially while other appliances are running. If the supply is stable and within spec, inspect all wiring connections from the outlet to the dryer's terminal block. If no external power issue is found, the main control board may need to be evaluated or replaced.
Is it safe to use my Bosch dryer when E:9024 is displayed?
You should not continue operating the dryer until the cause of the error has been identified. An unstable or out-of-spec power supply can damage the dryer's electronics over time and may indicate a wiring issue that poses a safety risk. Have the mains supply and electrical connections inspected before resuming use.
Will resetting my Bosch dryer clear the E:9024 error?
A reset may temporarily clear the error code, but if the underlying power supply issue is still present, the code will return. Simply resetting the dryer without addressing the root cause is not a long-term fix. The mains voltage and frequency should be checked and confirmed stable before assuming the problem is resolved.
How much does it cost to repair a Bosch dryer showing E:9024?
If the issue is external, such as an unstable utility supply or a faulty outlet, repair costs may range from nothing to around $50 to $150 for an electrician to inspect and correct the wiring. If the main control board is determined to be faulty after ruling out external causes, board replacement parts and labor can range from $150 to $400 or more depending on the specific model and service rates in your area.

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