Thetford fridge blinking red: reading the error code
A blinking red power LED with a flashing display is how a Thetford absorption fridge reports a fault. Whether you can simply read the number depends on which control panel your fridge was built with.
Getting the code out of the panel
On an LCD panel the code is already there: a spanner symbol with the number beside it. On an LED+ panel — the row of cooling-level bars, no numeric display — nothing is shown until you ask. While the display is blinking, hold all three buttons at once until it stops blinking. The bars that then light up are a binary number: from left to right they are worth 16, 8, 4, 2 and 1, and you add up the lit ones. Two bars lit at 8 and 4 means code 12. One important precondition from Thetford: with no 12 V DC at the control board, no error code is shown at all — a completely dead panel is an unpowered board, not a codeless fault.
Error code decoder (N3000 / N4000)
Read the number from the LCD, or add up the lit bars on an LED+ panel.
Flame when gas should be off
The board detects a flame although it has closed the gas valve — a safety report, not a cooling fault.
Burner module feedback wrong
Ignition electronics and main board disagree about the burner.
Gas lockout after 30 s
The burner did not light within 30 seconds. The most common gas-side code — usually no gas, no spark, or a misadjusted electrode.
12 V heater off when it should be on
Usually the 20 A DC fuse, a loose connection, or a failed element.
12 V heater on when it should be off
Board-side switching fault; a reset clears a one-off event.
12 V supply out of range
A supply fault, not a fridge fault. Note the manuals disagree on the lower limit — 10 V in English, 11.5 V in German.
No D+ engine-run signal
12 V selected by hand but the fridge cannot see the engine running. Reversed D+ wiring is a documented cause.
230 V heater current 75 % low
On mains the fridge is barely heating. Check the AC fuse — 4 A or 2 A depending on build date.
230 V heater on when it should be off
The mains-side twin of code 5.
230 V mains out of range
The accepted window depends on build date: 190–260 V after 08-02-2016, only 200–260 V before.
No energy source in AUTO
Often not a defect: mains unplugged, gas closed, engine off. Select each source by hand to reveal the real code behind it.
Display and power board lost contact
Disconnect 12 V for a full five minutes so the resettable fuse cools — a quick off-on does not do it.
Thermistor failed, backup mode
The fridge keeps cooling but blind. Check the sensor is even present — it often goes missing after a repair.
These 13 codes belong to the N3000 and N4000 absorption series. The older Premium LCD line (N90–N180, 2005–2012) has a different 1–14 table where the same numbers mean other things, and the T2000 compressor fridges use a third scheme again.
Check which family your fridge belongs to first
Thetford numbers its error codes per product family, and the tables do not transfer. Code 1 on an N3000 or N4000 means the board sees a flame when the gas should be off; on the older Premium LCD line, code 1 is a mains heater drawing 75 % too little current. Acting on the wrong table gives a confident, wrong answer.
The model number alone will not settle it either: N90, N97, N100, N104, N109, N112 and N145 all appear in both the Deluxe line and the Premium LCD line. Look for the series name on the data plate rather than trusting the bare number, and check whether the panel is an LED+ bar display or an LCD.
Most of these codes are about supply, not about the fridge
Five of the thirteen — codes 4, 6, 7, 8 and 10 — are the fridge reporting what arrives at its terminals rather than an internal defect. Code 6 is the 12 V rail out of range, code 10 the 230 V mains out of range, code 7 a missing engine-run signal, and codes 4 and 8 a heating element that is not drawing its expected current.
That has a practical consequence: measure at the fridge and while it is heating. An absorption fridge on 12 V draws around 15 A on a large model, so a thin or long supply cable shows up under that load and nowhere else. On mains, measure at the appliance rather than at the pitch bollard — a long extension lead is the usual reason a campsite supply falls out of the accepted window.
Two figures Thetford itself is inconsistent about
For code 6, the English troubleshooting document gives the lower limit as 10 V, while the German edition of the same N3000 document gives 11.5 V. Between those two values the manufacturer disagrees with itself about whether you have a fault at all.
For code 10, the accepted mains window depends on when the fridge was built: units after 08-02-2016 accept 190–260 V, earlier ones only 200–260 V. The same shore power can therefore be perfectly fine for one fridge and a reported fault for its neighbour on the next pitch.
Common questions
My Thetford fridge blinks red but shows no number. Where is the code?
You have an LED+ panel, which hides the code until you ask for it. While the display is blinking, hold all three buttons at once until it stops. The cooling-level bars that light up are a binary number worth 16, 8, 4, 2 and 1 from left to right — add the lit ones together.
The panel is completely dead. Which code is that?
None. Thetford states that with no 12 V DC supply at the control board, no error code can be displayed at all. Start with the 12 V supply and its fuse rather than looking for a code.
Does my fridge have to be an AES or automatic model to show codes?
It needs an electronic control panel. Fridges with a purely manual energy selector have no electronics to report anything. On the N4000 series the same model number can be supplied with either an LED+ or an LCD panel depending on how the caravan maker specified it, so the panel decides what you see — not the model number.
I found an error code list online and the numbers do not match my symptoms.
Very likely the list belongs to a different Thetford family. N3000 and N4000 use codes 1 to 13; the Premium LCD line built 2005 to 2012 uses its own 1 to 14 table with different meanings, and the T2000 compressor fridges use a third scheme. Confirm the series before you trust a number.
All documented Thetford refrigerator codes
Flame detected when the gas should be off. The board senses a flame although it has closed… Error code 2 warning
The burner control module returns incorrect feedback. The ignition electronics and the mai… Error code 3 warning
Gas lockout: the burner failed to light within 30 seconds, so the board shut the gas off. … Error code 4 warning
The 12 V heating element is off when it should be on. The board is calling for DC heating … Error code 5 warning
The 12 V heating element is on when it should be off. The board sees DC heating current it… Error code 6 warning
The 12 V supply is outside the permitted window. This is a supply fault, not a fridge faul… Error code 7 info
No "engine run" signal (D+) while the control is in manual 12 V mode. The fridge is set to… Error code 8 warning
The 230 V heating element is drawing at least 75 % less current than it should. On mains t… Error code 9 warning
The 230 V heating element is on when it should be off. The board detects mains heating it … Error code 10 warning
The 230 V mains supply is out of range. Like code 6 on the DC side, this reports the quali… Error code 11 info
No energy source is available while the control is in AUTO mode. The fridge looked for gas… Error code 12 warning
The display board and the power board have lost communication with each other. The two hal… Error code 13 warning
The thermistor has failed and the control has switched itself to the Backup Operation Syst…