You may want to call an HVAC guy to come out to fully inspect the heater. They can also do a carbon monoxide test. I believe SDGE may even do that. However getting an HVAC company out there will provide a more comprehensive inspection and they will be able to back your claim for either a new heater or credit at COE towards a new heater. If there is a carbon monoxide issue then you will have a safety issue and will want to know about that anyways.