My Goodman furnace shows a one blink code that translates to ignition failure and suggests checking the flame sensor (which I replaced) the gas valve (which I replaced) gas pressure (had new gas meter installed) or restricted gas flow (which I can't imagine) Any help is greatly appreciated.

Is the igniter working(glowing) when it should be?

The steps for a furnace to start up and work proper
1. the thermostat calls for heat
2. the inducer motor starts up (maybe for 30 sec.
3. the igniter comes on (glows)
4. the gas valve then opens and burners fire up
5. after maybe 1 minute the blower comes on and blows heat into ductwork which routes heat into house

The gas valve won`t open up until the igniter comes on

Observe operating sequence, should go like this: 1) inducer starts/runs, 20-40 seconds 2) ignitor glows, 17-34 seconds 3) gas control opens & burners light, 25-40 seconds 4) blower starts/runs for duration of heating cycle. Post back.

is the igniter working(glowing) when it should be?

the steps for a furnace to start up and work proper
1. the thermostat calls for heat
2. the inducer motor starts up (maybe for 30 sec.
3. the igniter comes on (glows)
4. the gas valve then opens and burners fire up
5. after maybe 1 minute the blower comes on and blows heat into ductwork which routes heat into houseDamn! It's true, great minds do think alike...

My Goodman furnace shows a one blink code that translates to ignition failure and suggests checking the flame sensor (which I replaced) the gas valve (which I replaced) gas pressure (had new gas meter installed) or restricted gas flow (which I can't imagine) Any help is greatly appreciated.

You may have replace the flame sensor and gas valve and didn`t need to,, the flame sensor very seldom goes bad,, (just needs cleaning with fine sandpaper)
The gas valve won`t open till the flame sensor sees the igniter glowing

The gas valve is not opening and so the burners do not light.

The igniter is glowing hot

The igniter isworking but the gas valve is not

Check the string of limit switches that surround the burner assembly. Follow the purple wires from one to the next, press the tab in the center, see if any of them are popped. If so you may have a heat exchanger leak.

Is there a way to bypass the limits directly to see if the limit connections are bad?

Follow my earlier suggestion and check for any that are popped. This is the next step, trust me. These are there for a reason and should not be bypassed.

Also ,how can you find a leak in the heat exchanger?

Observe. If the flames start blowing stray when the blower starts, you have a problem. If the burner limit(s) are tripped, it's a bad sign that this is happening.

None of the switches are popped and I have 28 volts at the gas switch

The burners never come on

Do you hear the gas valve clicking during the ignition trial? If not, turn power off, pull wires off gas valve, and check continuity of gas valve coil.

The gas valve does not click .There is a click at the circuit board after the igniter glows but the burners do not light and the blower does not come on

If you have a voltmeter, set it to ohms function and check gas valve coil. Infinite resistance would indicate a failed coil. Check for terminal oxidation while you're at it.

I will do that now. Thanks for paying attention!

The gas valve coil tower , if Iunderstand this is what you mean, is located in the gas valve itself. It is new and so are the connections. The ohm meter checked at these two terminals do not go to infinity but do show a little resistance

Sorry, I remember now that you replaced this. So many threads, so little memory... you were getting 28v at gas valve during ignition trials but no click from valve? Is valve switch on?

What are the terminal designations on the gas valve - "TH" & "TR", or "P", "C", & "M"? If the latter is true, is there a jumper between "P" & "M"?

It is M and C and there is no jumper between m and p as p is blank

Okay, try this: set voltmeter to AC amps function (make sure probes are connected to the right inputs), attach one probe to "M" terminal and one to wire removed from "M" terminal. Now turn heat on and see if you measure any amperage during ignition trial (when you hear click from gas valve relay on circuit board). If you do but hear no click from gas valve, the valve is bad, likely stuck closed.

No click at the gas valve the switch is on

Did you measure any amperage?

KC13 and wmproop you guys did a lot to help me out and I greatly appreciate it. My problem was the als and now it is working and my house is now warm. Thank you!

Continuity test,, the wireing on each end . Pull the wires loose from each limit switch and use the same tester to see if they are open

razorface agrees: this post is better than the gospel

Sorry to disagree,, nothing is better than the gospel