Goodman Furnace 4 Flashes: Open Limit Circuit
Four flashes on a single-LED Goodman furnace means a limit circuit is open: a temperature safety switch has tripped, the circulator blower keeps running, and the burners stay off. Which switches the manual names depends on the revision. The current *MES80 and *MSS9* charts say "Primary or auxiliary limit circuit is open." The GMH95 chart went the other way, from "primary or auxiliary" in its 2007 revision to "•Primary limit circuit is open." in 2012. On a *MEC96, red four is the open limit circuit, but amber four, "•Ylo or Y call present without G", is a thermostat-signal fault.
| Code | 4 flashes (Open limit switch) |
|---|---|
| Applies to | Single-LED Goodman series *MES80, *MSS9* and GMH95, and the three-colour *MEC96 (red 4 only); display series show a primary limit fault as EE3 or E3 |
| Severity | Unit will not run |
| DIY | Check, then call — owner-level checks first, then a dealer |
| Last checked |
What do 4 flashes mean, series by series?
Every single-LED Goodman chart here ties four flashes to the limit circuit, and every one gives the same symptom: "Circulator blower runs continuously. No furnace operation." What changes is the list of switches. Read the row for your series and, if you can, the revision printed on your own manual's back page.
| Series | Manual, revision, page | Goodman's wording (verbatim) |
|---|---|---|
| *MES80 / *CES80 | IOG-2021G (08/2021), flash code list p. 25 | Open Main or Auxillary Temperature Limit Switch |
| *MES80 / *CES80 | IOG-2021G (08/2021), chart p. 30 | • Primary or auxiliary limit circuit is open. |
| *MES80 / *CES80 | IOG-2021D (03/2020), chart p. 30 | • Primary or auxiliary limit circuit is open. |
| *MES80 / *CES80 | IOG-2021A (05/2019), chart p. 33 | •Primary limit circuit is open. |
| *MSS9* / *CSS9* | IOG-2009E (10/2015), flash code list p. 40 | 4 flashes, then pause: Open limit switch |
| *MSS9* / *CSS9* | IOG-2009E (10/2015), chart p. 43 | •Primary or auxiliary limit circuit is open. |
| GMH95 / GCH95 | IO-299P (10/2012), chart p. 43 | •Primary limit circuit is open. |
| GMH95 / GCH95 | IO-299B (7/07), chart p. 36 | •Primary or auxiliary limit circuit is open. |
The meaning changed between revisions, in opposite directions. The *MES80 widened it: revision A (2019) named only the primary limit, and revisions D (2020) and G (2021) added the auxiliary limit. The GMH95 narrowed it: the 2007 manual named primary or auxiliary, the 2012 manual names only the primary limit. If your manual and this table disagree, your manual's revision is the one written for your furnace.
On the *MEC96, red and amber four are different faults
The *MEC96 has a three-colour LED and a longer list of limit codes than the single-LED series. Its chart (IOG-2011U, pp. 54–55) splits limit trouble across three red counts, two of them defined by how long the circuit stays open, and gives amber four a meaning unrelated to temperature.
| LED signal | Goodman's fault description (verbatim) | Page |
|---|---|---|
| Red: Four repeating flashes | •Open limit circuit, main limit, aux limit, or roll out switch | 55 |
| Red: Five repeating flashes | •Limit & rollout circuit open for 15 minutes. Open control board fuse or rollout switch | 55 |
| Red: Eleven repeating flashes | •Open limit switch circuit for more than 5 minutes | 55 |
| Amber: Four repeating flashes | •Ylo or Y call present without G | 54 |
Amber four is about the cooling and fan signals from the thermostat. The chart's corrective-action column for it reads "•Faulty thermostat or thermostat wiring or improperly connected thermostat wires", the same as amber three.
The same fault on Goodman furnaces with a display
Display furnaces show the open primary limit as a code rather than four flashes. The three-character series print EE3, the two-character *MVM96 and *MVM97 print E3, and two series give the auxiliary limit in the blower compartment a code of its own, EEd. Rollout switches have separate codes again.
| Series | Display | Goodman's wording (verbatim, first item of the cell) | Manual, page |
|---|---|---|---|
| *M9C96 / *C9C96 | EE3 | Primary limit circuit is open | IOG-2027B, p. 45 |
| *M9S96 / *C9S96 / *M9S92 | EE3 | Primary limit circuit is open | IOG-2029A, p. 43 |
| *MVC80 / *CVC80 | EE3 | Primary limit circuit is open | IOG-2023A, p. 34 |
| *MVC80 / *CVC80 | EED | Aux limit switch open (blower compartment) | IOG-2023A, p. 36 |
| *M9S80*U | EE3 | Primary limit circuit is open; label p. 32: "Open High Limit Switch" | IOG-2031A, p. 28 |
| *M9S80*U | EEd | Auxiliary limit switch (blower compartment) circuit is open | IOG-2031A, p. 29 |
| *MVM96 / *CVM96 | E3 | • Primary limit.; code list: "OPEN HIGH LIMIT SWITCH" | IO-406E, pp. 53, 57 |
| *MVM97 / *CVM97 | E3 | • Primary limit.; code list: "OPEN HIGH LIMIT SWITCH" | IOG-2007E, pp. 56, 61 |
E11 is the one to watch on these controls: it is "Open roll out switch" on the *M9C96, *M9S96 and *MVC80, but "Burner limit switch circuit is open" on the *M9S80*U. The Goodman codes hub has the full lists and the other codes that change meaning between series.
What Goodman's charts list as causes
The single-LED charts give the same causes for four flashes, and one of them is airflow. This is the *MES80 revision G row (p. 30); the *MSS9* (IOG-2009E p. 43) carries the same list, typo "pirmary" included, and the GMH95 (IO-299P p. 43) has it in a different order with "primary" in place of "primary or auxiliary".
| Possible causes, IOG-2021G p. 30 (verbatim) |
|---|
| • Faulty primary or auxiliary limit switch. |
| • Insufficient conditioned air over the heat exchanger. Blocked filters, restrictive ductwork, improper circulator blower speed, or failed circulator blower. |
| • Loose or improperly connected wiring. |
"Blocked filters" is the only cause on that list an owner is allowed to deal with, and the chart's own corrective action for it is "• Check filters and ductwork for blockage. Clean filters or remove obstruction." Replacing a limit switch, changing the blower speed and correcting wiring are servicer work; the row's notes start with "• Turn power OFF prior to repair."
What you can check, and what to leave alone
A limit switch opens because heat is building up where it shouldn't. Goodman's manuals let an owner deal with the filter and look at the flame, and they print one emergency instruction for overheating that every owner should know before touching anything else.
| Task | Goodman's wording (verbatim) | Who |
|---|---|---|
| If it is overheating | "Should overheating occur or the gas supply fail to shut off, turn off the manual gas shutoff valve external to the furnace before turning off the electrical supply." (IOG-2011U p. 3; IOG-2021G p. 4) | Owner, in an emergency |
| Filter | "Improper filter maintenance is the most common cause of inadequate heating or cooling performance." (IOG-2011U p. 52; IOG-2021G p. 26) | Not marked servicer-only |
| Burner flame | "Visually inspect the burner flames periodically during the heating season." (IOG-2011U p. 53) | Not marked servicer-only |
| Annual inspection | "The furnace should be inspected by a qualified installer, or service agency at least once per year." (IOG-2011U p. 52) | Installer or service agency |
| Flame sensor | "Flame Sensor (Qualified Servicer Only)" (IOG-2011U p. 53; IOG-2021G p. 27) | Qualified servicer |
Goodman's *MES80 manual also asks owners not to open the burner compartment: "To prevent personal injury or death, do not remove any internal compartment covers or attempt any adjustment. Electrical components are contained in both compartments. Contact a qualified service agent at once if an abnormal flame appearance should develop." (IOG-2021G p. 27)
Why repeat limit trips need a servicer
One trip after a clogged filter is changed may be the end of it. A furnace that keeps returning to four flashes is overheating for a reason the filter didn't fix, and the remaining causes on Goodman's list are parts and settings inside the cabinet. The *MEC96 chart shows how the control itself escalates: red eleven flashes is an open limit circuit "for more than 5 minutes", and red five is "Limit & rollout circuit open for 15 minutes".
- Four flashes comes back after the filter has been cleaned or replaced.
- A *MEC96 moves on to red five or red eleven flashes, or a display furnace keeps showing EE3, E3 or EEd.
- The burner flame looks abnormal: Goodman's instruction is to contact a qualified service agent at once.
- The furnace keeps heating when it should stop, or the gas does not shut off: use the manual gas shutoff valve first, as Goodman instructs.
Goodman's safety wording
The manuals cited here print their gas-leak instruction near the front, for example on p. 3 of IOG-2011U and IOG-2021G and p. 4 of IO-299P. The table repeats it in Goodman's words with the carbon monoxide warning that sits beside it.
| Goodman's wording (verbatim) | Source |
|---|---|
| "WHAT TO DO IF YOU SMELL GAS: • Do not try to light any appliance. • Do not touch any electrical switch; do not use any phone in your building. • Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. • If you cannot reach your gas supplier, call the fire department." | IOG-2031A, p. 3; same instruction in IOG-2011U, IOG-2021G, IOG-2009E (p. 3) and IO-299P (p. 4) |
| "Possible property damage, personal injury or death due to fire, explosion, smoke, soot, condensation, electrical shock or carbon monoxide may result from improper installation, repair operation, or maintenance of this product." | IOG-2011U, p. 3 |
Frequently asked questions
What does 4 flashes mean on a Goodman furnace?
On the single-LED *MES80, *MSS9* and GMH95 it means a limit circuit is open, so the blower runs and the burners don't. On a *MEC96, red four is "Open limit circuit, main limit, aux limit, or roll out switch" and amber four is a thermostat signal problem.
Why does my Goodman manual say "primary limit" when this page says "primary or auxiliary"?
Because Goodman changed the wording between revisions. The *MES80's 2019 manual said primary only and later revisions added auxiliary, while the GMH95's 2007 manual said primary or auxiliary and its 2012 manual says primary only. The table above lists each revision.
Can a dirty filter cause 4 flashes on a Goodman furnace?
Yes, it is on Goodman's list. The single-LED charts give "Blocked filters" as part of "Insufficient conditioned air over the heat exchanger", and the matching action is to check filters and ductwork and clean the filters or remove the obstruction. It is not the only cause on the list.
What should I do if my Goodman furnace is overheating?
Follow Goodman's own instruction: "Should overheating occur or the gas supply fail to shut off, turn off the manual gas shutoff valve external to the furnace before turning off the electrical supply." Then call a qualified servicer rather than restarting the furnace.
What is the display code for an open limit on a Goodman furnace?
EE3 on the *M9C96, *M9S96, *MVC80 and *M9S80*U, and E3 on the *MVM96 and *MVM97. The *MVC80 and *M9S80*U also have a separate code, EED or EEd, for the auxiliary limit switch in the blower compartment.