Why Is My Hot Water Pressure Low?
If only the hot water trickles while cold runs strong, the problem is on the hot side—often the heater. Here's what's going on.
Read more →Common Water Heater Error Codes (and What They Mean)
That blinking light or numbered code is your heater telling you what's wrong. Here's how to read the most common ones.
Modern water heaters—especially tankless and newer gas units—use blinking lights or numbered codes to report faults. Codes vary by brand, but the categories are consistent. Here's how to decode the most common ones. Always check your unit's manual for the exact meaning.
Gas tank units: blinking status light
- Slow steady blink — normal operation
- Specific blink patterns — often a thermocouple/thermopile, pilot, or gas-valve fault
- No light — usually a dead thermopile or control failure
Tankless error codes (common themes)
- Ignition failure codes — gas supply, igniter, or flame-sensor issue
- Flame-loss codes — interrupted gas or venting problem
- Scale/overheat codes — the heat exchanger needs descaling
- Venting/air codes — blocked intake or exhaust
- Flow-sensor codes — mineral buildup or sensor fault
On tankless units, a large share of error codes trace back to one cause in NJ: hard-water scale. Annual descaling prevents many of them.
What you can safely check
- Confirm the gas is on and other gas appliances work
- Check that the unit has power and the breaker isn't tripped
- Make sure intake and exhaust vents are clear of obstructions
- Reset the unit once per the manual—if the code returns, call a pro
When to call us
Repeated codes, ignition failures, or anything involving gas should go to a licensed technician. We diagnose and repair every major brand—book a repair or, if you have no hot water and can't wait, emergency service. Call 973-834-8833.
Good to Know
Frequently Asked Questions
Why does my tankless water heater keep showing an error code?
Recurring codes often point to hard-water scale, a venting issue, or a gas-supply problem. Descaling resolves many; persistent codes need a technician.
Can I reset my water heater myself?
You can perform the manufacturer's reset once. If the same code returns, stop and call a professional rather than repeatedly resetting.
Need a hand from a licensed NJ water heater pro? Hot Water NJ installs, repairs, and replaces every type of water heater across Northern New Jersey—usually same day. Call 973-834-8833 or request a free estimate below.