<\/figure>\n\n\n\nI have included some of the more common Bosch hot water error codes that I come across shown below.<\/p>\n\n\n\n
Bosch Tankless Error code A2 – Problem with the flue gas limiter<\/h3>\n\n\n\n The temperature of the flue gases is too high and is above 230 F. Check for gas leakages or constant flame on the burner. This temperature sensor is located at the top-right corner of the unit.<\/p>\n\n\n\n
Bosch Error code A3 \u2013 Wire harness fault <\/h3>\n\n\n\n Measure the resistance on the wire harness; it must be between 115 and 120 ohms.<\/p>\n\n\n\n
Bosch Error code A4 – Backflow temperature sensor<\/h3>\n\n\n\n Check the backflow temperature sensor connection for rust or damage. It could also be short-circuited. It is located below the heat exchanger and ignition electrodes. Look for the diagnostic menu 1P and nC code.<\/p>\n\n\n\n
Bosch Error code A7 \u2013 Outlet temperature sensor fault<\/h3>\n\n\n\n The outlet temperature sensor reacts when the temperature is either below 36 F when the unit is protected from freezing temperatures. Also above 210 F in a case of overheating due to the lime-scale deposits. Check the sensor and wiring for scale, rust, or damage. You might have to flush the unit to remove the mineral scale build-up.<\/p>\n\n\n\n
This fault results from the temperature thermistor on the right-hand side of the heat exchanger failing to give a temperature indication. This fault will not stop the heater from operating, but will first display ’00’ on the ICU display before changing to ‘A7’ on the ICU display. Ensure wiring connections to the thermistor. If this does not rectify the fault, test thermistor readings in ohms in conjunction with the thermistor chart to assess correct readings.<\/p>\n\n\n\n
Bosch Error code A9 \u2013 Outlet temperature sensor fault<\/h3>\n\n\n\n This A9 error code is associated with the outlet temperature sensor, but this time, the sensor is not sensing the expected output temperature. This is not an error code; it is a flashing status message that tells you to check; the wiring connection, gas pressure as it might be too low, voltage as it doesn’t meet the required 120\/240 VAC, the unit that might not be properly grounded or the issue with the control board.<\/p>\n\n\n\n
Bosch Error code C6 \u2013 Slow-spinning fan<\/h3>\n\n\n\n The primary extraction fan spins slowly when the water heater is working. Check the wiring connection on the fan and control board. The voltage must be 120\/240 VAC and the element correctly grounded. Does the venting system meet the code and manufacturer requirements? Ensure that the gas pressure is as required because the low pressure leads to fan rotation problems.<\/p>\n\n\n\n
Bosch Error code C7 \u2013 Fan rotational speed sensor<\/h3>\n\n\n\n No signal from the fan’s rotational speed sensor. The sensor might be broken. Check the wire connection on the control board and fan. The voltage needs to be 120\/240 VAC and adequately grounded. Ensure that the fan and control unit is not damaged.<\/p>\n\n\n\n
Bosch Error code CA \u2013 Excessive water flow<\/h3>\n\n\n\n Make sure that the water pressure is less than 150 PSI and a flow rate below 10 GPM. Check the wire connections on the water valve and control panel.<\/p>\n\n\n\n
Bosch Hot Water Error Code 11<\/h3>\n\n\n\n The Bosch gas hot water fault code 11 signifies that there is a fault with the unit\u2019s ignition. In this instance, your Bosch hot water heater will not operate and won\u2019t produce hot water until Bosch fault code 11 has been investigated and repaired.<\/p>\n\n\n\n
Bosch Error code E1 \u2013 Extremely high temperature<\/h3>\n\n\n\n The temperature detected by the outlet temperature sensor is over 185 F. Ensure that the sensor is working correctly, and the wire connections are not loose. Another reason for the high temperature is the sediment build-up, so descaling and flushing will be required.<\/p>\n\n\n\n
Bosch Error code E2 \u2013 Faulty inlet water temperature sensor<\/h3>\n\n\n\n Check the sensor and wiring connections for corrosion as this sensor is in charge of protecting the unit from freezing. <\/p>\n\n\n\n
Bosch Error code E3 \u2013 Problem with the exhaust temperature sensor<\/h3>\n\n\n\n The unit will shut down if the temperature of the exhaust gases is above 194 F. Check and clean the heat exchangers if needed. Reduce the maximum power and water temperature.<\/p>\n\n\n\n
Bosch Error code E4 \u2013 Problem with the backflow temperature sensor<\/h3>\n\n\n\n The backflow temperature sensor reacts when the temperature is over 309 F. Check the vent pipes if they meet the code and requirements, look for damages and obstructions.<\/p>\n\n\n\n
Bosch Error code E9 \u2013 Overheat sensor ECO has an open circuit <\/h3>\n\n\n\n Check the wire connections on the sensor and control board. Ensure the venting system is per codes and instructions. Descale the unit if necessary.<\/p>\n\n\n\n
Disconnect the wires from the temperature thermistor (over-temperature sensor) on the right-hand side of the heat exchanger, and test the resistance of the thermistor. If the resistance is greater than 0.1 ohm, replace the thermistor.<\/p>\n\n\n\n
Bosch Error code EA \u2013 No sparks for the electrodes<\/h3>\n\n\n\n The ionization electrodes are not making sparks when water is flowing. There are many reasons for this problem and here are some possible issues; low gas pressure, the fan speed is low, wire connections are loose, the air in the gas line, no gas corroded connections, dirty electrodes.<\/p>\n\n\n\n
Failure to ignite will cause Safety Time Out. Three possible causes are <\/p>\n\n\n\n
1. Ignition failure due to insufficient gas supply. Check the gas supply to the unit, Correct if necessary. <\/p>\n\n\n\n
2. Flame rod not detecting pilot flame. Check the wiring connection to the ICU. Measure the flame rod current (should be 10 – 12 \u00b5A DC). Check the condition of the pilot flame, and if dirty, clean or replace the injector. If the pilot is clean, and the voltage from the flame rod is correct, replace the ICU. <\/p>\n\n\n\n
3. If the pilot is failing to light, measure the voltage to the orange pilot solenoid (should be 0.9 – 1.2 Volt DC). If the voltage is correct, replace the solenoid. If the voltage is incorrect, replace the ICU. (note:- always check the voltage with the wiring connected)<\/p>\n\n\n\n
Bosch Error code EC \u2013 Electrode failure<\/h3>\n\n\n\n Ionization electrode failure during water heating. The reasons might be; obstructed venting system, low gas pressure, and CO2 readings, the fan speed could be too low.<\/p>\n\n\n\n
Bosch Error code E0 hardware\/software issues<\/h3>\n\n\n\n The issue with the hardware or software. First, try to reset the error code and turn the hot water unit off and back on. There might be an issue with the computer. Check if the wire connections are properly linked to the computer board or the board is not damaged.<\/p>\n\n\n\n
Bosch Error code F7 \u2013 Ionization rod problem<\/h3>\n\n\n\n The problem is with the ionization rod at standby. Check connections to the electrodes for corrosion and tightness. It should be securely connected. Other reasons might include damaged elements or a faulty control board.<\/p>\n\n\n\n
This fault can result from an earthing problem with the flame sensor rod or an ignition pack failure. Clean the flame rod and ensure the wires are adequately connected. If the fault remains, replace both the flame sensor rod and the ICU.<\/p>\n\n\n\n
Bosch Error code FA \u2013 Gas valve circuit<\/h3>\n\n\n\n The problem is with the gas valve circuit. Check the wire connections on the gas valve and control board. Measure the voltage on the wires when a water heater is ON\u2026 it should be 24 VDC. If the measurement is not as specified, the gas valve is malfunctioning. Check for correct gas pressure and that the gas valve is operating by putting 24v onto the valve.<\/p>\n\n\n\n
Conclusion<\/h2>\n\n\n\n Check out this post on DIY Bosch tankless water heater troubleshooting<\/a> if your remote controller is working fine. There is also a more in-depth list of error codes included in that post.<\/p>\n\n\n\nBosch hot water units are very reliable and only tend to fail when there is moisture in the PCB, so keep them dry. Avoid installing remote control units in wet areas like bathrooms and laundry.<\/p>\n","protected":false},"excerpt":{"rendered":"
I love my Instantaneous Bosch High Flow Gas 26e Hot Water unit. It gives me and the family endless hot water whenever we want. Well until the other day when we had no hot water. I thought no problem, maybe the pilot light didn’t light or something? So How to Repair Bosch Hot Water Controller? […]<\/p>\n","protected":false},"author":1,"featured_media":653,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[165,395],"tags":[139,205,204,203],"yoast_head":"\n
How to Repair Bosch Hot water controller like the YPRM66XB Easy<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n \n \n\t \n\t \n\t \n