An error code almost never means your surge protector has failed. It means the unit has examined the pedestal, found something wrong, and is refusing to pass that problem on to your rig. That is the job you bought it to do.
The exception is the code that reports the unit’s own surge module as spent —
E-10 on Progressive Industries units, REPLACE SURGE on Surge Guard. Those
two are about the protector rather than the post.
Before you read the chart
Two things worth establishing, because they change what the code means.
Is the unit refusing to connect, or reporting and carrying on? Some conditions cut power. Others display a warning while power continues. On Progressive units a displayed code with no power reaching the rig is a disconnect; on Surge Guard units the caution LED flashes whenever any fault is present.
Has it just been plugged in? Both brands run a startup delay before connecting — Surge Guard counts down 128 seconds. A display showing a countdown is not a fault.
Progressive Industries E-codes
Taken from the manufacturer’s error code chart for the EMS range. The same numbering is used across the portable and hardwired units, with the Line 2 codes applying only to 50 amp models.
| Code | Meaning | What to do |
|---|---|---|
| E-0 | Normal condition | Nothing. This is the healthy state. |
| E-1 | Reverse polarity — hot and neutral reversed | Do not use this pedestal. Report it. |
| E-2 | Open ground | Shock hazard. Move to another post and report it. |
| E-3 | Line 1 voltage high, above 132V | Wait, or move. Sustained high voltage damages appliances. |
| E-4 | Line 1 voltage low, below 104V | Usually campground demand. Shed load or move. |
| E-5 | Line 2 voltage high, above 132V | 50 amp only. As E-3, on the second leg. |
| E-6 | Line 2 voltage low, below 104V | 50 amp only. As E-4, on the second leg. |
| E-7 | Line frequency high, above 69 Hz | Almost always a generator problem, not shore power. |
| E-8 | Line frequency low, below 51 Hz | As E-7. Check the generator’s governor or load. |
| E-9 | Data link down | Communication fault between unit and remote display. |
| E-10 | Replace surge protector module | The unit’s surge protection is spent. |
PE codes: what happened while you were asleep
This is the most useful feature on a Progressive unit and the least understood.
When the EMS disconnects, it displays a PE code after the E code showing the previous error — the condition that caused the last shutdown. The code clears when the unit is disconnected from power.
That matters because most faults are transient. If your air conditioning stopped overnight and everything looks normal by the time you check, the PE code tells you whether the supply sagged, spiked or lost its ground. Without it you are guessing.
If you unplug the unit to “reset it” before reading the PE code, you have discarded the only evidence of what went wrong.
Surge Guard LCD messages
Surge Guard units display plain text rather than numbers. From Southwire’s instruction sheet for models 34930 and 34950:
| Display | Meaning | What to do |
|---|---|---|
| REPLACE SURGE | Surge protection expended | Unit still passes power but no longer protects against surges. Replace it. |
| OPEN GROUND | No ground connection | Shock hazard. Different pedestal. |
| REVERSE POLARITY | L1 or L2 wired to neutral or ground | Do not use. Also shown for voltage on ground. |
| L1 HIGH / L2 HIGH | Voltage above 136V | Wait or move. |
| L1 LOW / L2 LOW | Voltage below 102V | Usually demand. Shed load or move. |
| OPEN NEUTRAL | Open neutral on the coach side | Stop. See below. |
| NEUTRIP | Neutral current above 130% | 50 amp models. Load imbalance between legs. |
| L1 AMPS | Current above 110% | You are drawing more than the supply likes. |
| RECEPT OVERHEAT | Plug or receptacle overheating | Fire risk. Stop using this pedestal. |
| GND HIGH | Abnormal voltage on ground | Do not use this pedestal. |
The displayed message usually includes the measured value — L1 LOW WAS 99V —
which is genuinely useful. It tells you how far out of range the supply went,
not merely that it did.
Hughes Power Watchdog indicators
Hughes reports differently again — mostly through the app, with the unit itself signalling the one condition you must not miss.
| Indicator | Meaning | What to do |
|---|---|---|
| WatchDog logo turns red + E9 in the LCD window | Surge module spent | Replace the module. Voltage protection still works |
| Gen I base models (PWD30/PWD50): one or both lights below the main three go out | Surge module spent | As above |
| Faults reported in the app | High/low voltage, open ground, open neutral, overcurrent | As the equivalent conditions below |
If a Gen II unit will not report anything at all, check two things before assuming a fault: Hughes runs three separate apps by generation, and Gen II WiFi units connect only to a 2.4 GHz SSID. Details in our Power Watchdog review.
The same faults, by what they actually mean
If your unit is a brand not listed above, the underlying conditions are the same and only the labels differ.
| What you see | Likely cause | What to do | Who |
|---|---|---|---|
| Low voltage | Campground demand, long undersized supply run, or a weak generator | Shed load or change pedestal. Do not run the A/C on it | Easy |
| High voltage | Utility problem, or a miswired 240V connection reaching a 120V circuit | Disconnect. Report it — this damages appliances quickly | Easy |
| Open ground | Pedestal ground wire disconnected or never terminated | Move pedestal, report to the campground office | Easy |
| Open neutral | Neutral conductor broken or disconnected | Disconnect immediately. Highest-risk pedestal fault there is | Technician |
| Reverse polarity | Hot and neutral swapped at the post | Move pedestal. Common in older parks | Easy |
| Voltage on ground | Current finding a path through the grounding conductor | Disconnect. Report it as a safety issue | Technician |
| Receptacle overheating | Loose or corroded connection generating resistance heat | Stop using that pedestal. Fire risk | Technician |
| Surge module expended | The unit absorbed a surge and used up its protection | Replace unit or module. Voltage protection still works | Easy |
| Frequency out of range | Generator governor problem — very rare on shore power | Investigate the generator, not the pedestal | Moderate |
Is it the unit or the pedestal?
One test settles it, and it costs nothing: plug into a different pedestal.
- Fault follows you → the problem is your rig or the unit. Check the shore cord and plug pins first, since a damaged plug produces faults that look like pedestal problems.
- Fault stays behind → the post was the problem. Tell the campground office; an open ground or open neutral is their problem to fix and other people will plug into it after you.
If you have no second pedestal available, a known-good domestic outlet with an appropriate adapter will tell you the same thing for the voltage and wiring checks.
The other common misreading is assuming the unit has failed because it will not connect. A unit that refuses a bad pedestal is working. A unit that shows nothing at all on a known-good supply may genuinely have failed — that is a different symptom.
Which codes mean stop
Most codes mean wait or move. These mean disconnect and do not reconnect here:
- Open neutral — can put dangerous voltage across the whole rig at once
- Voltage on ground / GND HIGH — current is flowing where it should not
- Receptacle overheating — a failing connection generating heat
- Reverse polarity — energised chassis-adjacent conductors
None of these are fixed by adapters, resets or patience. They are faults in someone else’s wiring, and the correct response is to use a different post and tell the site.
If your power keeps stopping but no code appears and nothing has physically tripped, that is a different diagnosis — see why your RV breaker keeps tripping.
Related guides
- EMS vs surge protector — why a basic surge protector shows you none of this.
- Best RV surge protectors — eight units compared, including which ones report faults in plain English.
- Progressive vs Power Watchdog — one reports codes on the unit, the other to your phone. That difference is most of the decision.
- Hughes Power Watchdog review — including the app and WiFi requirements behind most “it won’t connect” reports.
- Progressive EMS-PT30X review — including why the unit sits silent for two minutes before passing power.
- Surge Guard vs Progressive — plain English messages against numbered codes, and which brand cuts power sooner.
- Why does my RV breaker keep tripping? — when the problem is load rather than the pedestal.
- 30 amp vs 50 amp RV — why 50 amp units have Line 2 codes and 30 amp units do not.
Questions worth answering
Does an error code mean my surge protector is broken?
Almost never. A code means the unit has found something wrong with the supply and is telling you what. The one code that does indicate the unit itself needs attention is Progressive's E-10 or Surge Guard's REPLACE SURGE, both of which mean the surge module has been used up.
What is the difference between an E code and a PE code on a Progressive unit?
An E code is the condition now. A PE code is the previous error — the fault that caused the last shutdown. PE codes are useful for diagnosing something that happened overnight, and they clear when the unit is disconnected from power.
My unit shows E-2. Can I just use a different adapter?
No. E-2 is an open ground, meaning the pedestal has no ground connection. That is a shock hazard, not a compatibility problem, and no adapter fixes it. Report the post to the campground and move to another one.
The display says REPLACE SURGE but everything still works. Do I need to act?
Yes, though not urgently. It means the surge protection has been used up absorbing something. The unit still passes power and its voltage monitoring still works, but you no longer have surge protection, so the unit should be replaced or its module swapped.
Why does my unit show a code, then work fine a few minutes later?
Because the fault cleared. Voltage sags come and go with campground demand. After the supply returns to range, EMS units wait — 128 seconds on Surge Guard models — before restoring power, so the air conditioning compressor is not restarted too soon.
Can I bypass the surge protector to get power back?
You can, and it is a bad idea. The unit is refusing to connect because it found something it considers dangerous. Bypassing it puts that fault straight onto your rig, which is the specific scenario the unit was bought to prevent.