E17/ E18 Bosch Dryer Error Code Troubleshooting Guide

Bosch dryers are known for their durability, efficiency, and advanced technology. However, like any appliance, they can occasionally develop issues. Two common error codes that may appear are E17 and E18. These codes indicate a problem with the dryer’s NTC temperature sensors and must be addressed to resume normal operation.

What is an E17 Error Code?

An E17 error code indicates a problem with the NTC temperature sensor located at the lint screen, designated as R3. NTC stands for “negative temperature coefficient” – these sensors measure air temperature inside the dryer.

Specifically, an E17 code means the control module has detected issues communicating with the R3 sensor at the lint screen housing. It’s not receiving expected resistance values.

Potential causes of an E17 error include:

• Shorted or open wire in the R3 sensor circuit
• Faulty R3 NTC sensor
• Poor/loose connection of the R3 sensor wires

When an E17 is present, the dryer will immediately stop running a cycle. You must clear the error before the dryer can operate again.

Troubleshooting an E17 Error Code

Troubleshooting an E17 error involves systematically checking the sensor’s wiring and connections, determining if the circuit has continuity, and testing the NTC sensor itself. Here is the recommended procedure:

1. Check Wire Harness and Connections

The first step is verifying the wire harness between the R3 sensor and control module is intact. With the dryer unplugged, remove the top panel to access the wire harness. Check for any visible damage to the wires.

Then unplug the R3 sensor and inspect both ends of the connector. Look for broken or corroded pins or signs of overheating. Spray contact cleaner on the pins if they are corroded. Check that the sensor is plugged in tightly.

2. Check Wiring Continuity

Use a multimeter to check continuity through the wire harness. Set it to the continuity or ohms setting. Touch the probes to the pins at each end of the R3 sensor wiring.

You should get a low resistance reading, typically less than 1 ohm. If you get no continuity, there is a break in the circuit that must be repaired.

3. Check R3 Sensor Resistance

If the wiring checks out, the next step is testing the R3 sensor itself. The sensor contains a small thermistor that changes resistance according to temperature.

Consult the service manual for the exact specifications of your dryer’s R3 sensor. Typical values are:

• 10k ohms at room temperature
• 5.3k ohms at 104°F
• 3.6k ohms at 122°F

With the dryer unplugged, use a multimeter to measure the resistance between the sensor pins. Compare your reading to the specification for your model.

If the resistance deviates significantly from the specification, you likely need to replace the R3 sensor.

4. Replace Faulty Parts

If you find damage to the wire harness or connector pins, repair the broken circuit. If the R3 sensor is faulty, order and install a new one. Be sure to match it to your specific model. You can check the compatibility by using the compatibility tool on our website by clicking here.

Once any faulty parts have been replaced, reconnect the harness to the sensor, restore power, and try running a cycle. This should clear the E17 code.

What is an E18 Error Code?

Like an E17, an E18 indicates an issue with an NTC temperature sensor in the dryer. However, the E18 code specifically pertains to the R2 sensor located at the heater or burner housing.

The R2 sensor monitors air temperature near the heat source to prevent overheating. If the control module stops receiving readings from this sensor, it will show an E18 error and stop operation.

Causes of E18 error codes include:

• Shorted or open wire in the R2 sensor circuit
• Faulty R2 NTC sensor
• Loose connection of the R2 sensor wires

The troubleshooting procedure for an E18 is the same as outlined above for the E17. The only difference is checking the harness and connections for the R2 sensor instead of the R3.

Troubleshooting an E18 Error

Follow these steps to troubleshoot an E18 error code:

1. Check R2 Wire Harness and Connections

Visually inspect the R2 sensor wiring for damage. Check that the connector pins at both ends are clean, intact, and inserted tightly.

Look for corroded, broken, or burnt pins. Use contact cleaner if needed. Verify the harness is firmly plugged into the R2 sensor and control module.

2. Check Wiring Continuity

Using a multimeter on the continuity setting, check that there is an unbroken circuit through the R2 sensor harness. You should measure less than 1 ohm resistance.

If continuity is lacking, you must repair the severed wire.

3. Check R2 Sensor Resistance

Refer to your service manual for the correct room temperature resistance spec of the R2 sensor. For Bosch dryers, it’s typically around 25k ohms.

Using a multimeter, test the resistance between the R2 sensor pins. If it’s far off from the spec, the sensor will need replacement.

4. Replace Damaged Parts

If the wire harness, connections, or R2 sensor itself are faulty, order and install new replacement parts as needed. With repaired wiring and a functioning R2 sensor, the E18 code can be cleared.

Resetting Error Codes

Once any problems have been resolved, the error codes can be reset by cycling power to the dryer.

Unplug the dryer or turn off the circuit breaker for several minutes to clear any codes from the control module’s memory. When powered back on, normal operation should resume.

Preventing Overheating Faults

E17 and E18 codes indicate the dryer stopped due to elevated temperatures. To help prevent these and other overheating faults:

• Clean the lint filter before every load
• Check that the exterior vent hood is unblocked
• Use rigid metal ductwork, avoid crushing or excess bends
• Confirm the dryer vent meets maximum length guidelines
• Vacuum the dryer duct and vent hood annually
• Don’t overload the dryer drum

With proper maintenance and ventilation, you can improve the dryer’s airflow and help regulate operating temperatures.

More Information

We hope with this guide, you have an understanding of what’s causing the E17 and E18 error codes and the process for troubleshooting them yourself. If you have any other questions or need further assistance feel free to contact us at 1(877) 477-7278 and one of our pros will be happy to help.

For more appliance repair tips and troubleshooting guides, be sure to check out AppliancePartsPros.com. We have extensive resources on DIY fixes for dryers, refrigerators, dishwashers, washing machines, ranges, and more. Our website, Facebook page, and YouTube channel provide useful articles, videos, part schematics, and other materials to help you troubleshoot and repair your appliances.