C01 Error on Rheem PROG40-34N RH67 Gas Water Heater — Fix Guide

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• Source: Official Rheem service manual
• Reviewed by: Geo Technical Editorial
• Published: March 1, 2026
• Updated: March 1, 2026

Safety notice: Start with user-safe checks only. Do not open sealed refrigerant systems, inspect gas-train components, or work on energized high-voltage parts unless you are qualified to service this appliance.

Error C01 on Rheem : No pilot / ignition failure (gas). Follow the troubleshooting steps below to diagnose and fix this gas-water-heater issue. ## What Error Code C01 Means on a Rheem PROG40-34N RH67 Error C01 on the PROG40-34N RH67 indicates the gas burner failed to ignite within the allotted trial period. This is the most common gas water heater fault, usually caused by gas supply issues, a faulty igniter, or a dirty thermocouple. When C01 appears, the Rheem gas water heater pauses normal operation to protect internal components from potential damage. Not every C01 fault requires a professional engineer — many are resolved through careful inspection and routine maintenance. Work through each diagnostic step below in sequence, starting with the simplest check, to identify the root cause efficiently before considering part replacement or arranging a service call. ## Symptoms - Hot water runs out quickly or is cold

• C01 or ignition fault LED on status display
• Pilot flame is absent (visible inspection window on some models)
• Gas valve status light blinks fault pattern ## Common Causes - No pilot / ignition failure (gas) ## Tools You May Need - Flashlight
• Soft brush (for thermocouple cleaning)
• Gas leak detector ## Step-by-Step Repair Guide | Step | Action | Result | |------|--------|--------| | 1 | Check your home gas supply — confirm the gas valve at the water heater is fully open (parallel to the pipe). | Done — continue to step 2 if the issue persists. | | 2 | Inspect the pilot assembly through the observation window; if the pilot is out, follow the relight procedure on the water heater label. | Done — continue to step 3 if the issue persists. | | 3 | If the pilot fails to stay lit, the thermocouple may be faulty or needs repositioning closer to the pilot flame. | Done — continue to step 4 if the issue persists. | | 4 | Clean the pilot orifice and thermocouple tip with a soft brush if they appear corroded. | Done — continue to step 5 if the issue persists. | | 5 | If the pilot stays lit but the main burner won’t ignite, the gas valve or control module is likely faulty. | Done — if the fault remains, contact a qualified technician. | ## Safety Precautions Work near gas appliances requires caution. Always check for gas leaks before lighting. Never use open flame to check for leaks. ## Estimated Repair Time and Difficulty Most gas water heater error code C01 faults can be assessed and addressed in 30–90 minutes using the steps above. The diagnostic process requires only basic tools: a multimeter and standard screwdrivers cover the majority of checks described here. If a replacement part is required, allow 1–5 working days for delivery. A trained technician with access to the correct diagnostic equipment will typically resolve this type of fault within a single service visit. ## When to Call a Technician Contact a Rheem authorised service technician if: the fault persists after following all the steps above; if PCB-level or refrigerant-circuit work is required; or if you are not comfortable working with electrical or mechanical components. When calling, have the full model number, the error code displayed, and a brief description of any sounds or symptoms you noticed before the fault appeared — this helps the technician prepare the correct parts and tools. ## Frequently Asked Questions Q: How long should a Rheem pilot stay lit? A properly functioning pilot stays lit continuously in standby. If it goes out within seconds of releasing the pilot button, the thermocouple is not generating sufficient millivoltage (should be > 18 mV). Q: Is it safe to smell gas near the water heater? No. If you detect a strong gas smell, do not attempt relighting. Leave the building immediately and call your gas utility emergency line. ### Is it safe to keep using my Rheem with error C01? If error C01 does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the gas-water-heater with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error C01 on a Rheem ? Repair costs for error C01 on the Rheem gas-water-heater depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a Rheem-authorized service provider for an accurate estimate based on your specific situation. ### What does error code C01 mean on a Rheem gas-water-heater? Error code C01 on Rheem gas-water-heater models indicates No pilot / ignition failure (gas). This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue. ### Is it safe to keep using my Rheem with error C01? If error C01 does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the gas-water-heater with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error C01 on a Rheem ? Repair costs for error C01 on the Rheem gas-water-heater depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a Rheem-authorized service provider for an accurate estimate based on your specific situation. ### What does error code C01 mean on a Rheem gas-water-heater? Error code C01 on Rheem gas-water-heater models indicates No pilot / ignition failure (gas). This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue.