Thetford Refrigerator: “Error code 13”
warning RV refrigerator error codes
What it means
The thermistor has failed and the control has switched itself to the Backup Operation System. The fridge keeps cooling, but blind: without a working temperature sensor it can no longer regulate to the setting you chose. How you read this code depends on the control panel. An LCD panel shows a spanner symbol with the number next to it. An LED+ panel shows nothing until you ask for it: while the display is blinking, hold all three buttons at once until it stops, and the cooling-level bars that then light up are a binary number — the five bars are worth 16, 8, 4, 2 and 1 from left to right, added together. And note Thetford's own warning: with no 12 V DC at the control board, no error code is shown at all.
Most likely causes
- Thermistor unplugged or not seated in its connector most likely
- Thermistor missing entirely after a service common
- Wiring loom not connected properly to the power board common
- Broken sensor cable, or bent/loose pins in the plug common
- Thermistor itself failed common
Safe checks you can do yourself
- Check the thermistor is actually there — Thetford's flow starts by asking whether it is present at all, which tells you how often it goes missing after a repair.
- Confirm it is plugged in correctly and that the wiring loom is properly connected to the power board.
- Inspect the plug for pins that are bent, loose or pushed back, and straighten what can be straightened.
- Measure continuity of the sensor cable before replacing the sensor — a broken cable looks exactly like a dead thermistor.
How to reset / clear Error code 13
- Reconnect or replace the thermistor first, then switch the fridge off and on.
- Give it a full cooling cycle before judging: with Backup Operation the fridge runs to a fixed pattern, so temperatures behave differently until the sensor is back.
When to call a technician
Sensor, cable and connectors are all sound and code 13 remains — Thetford then points at the service kit or power board depending on build date.
Accuracy notes
The number alone is not enough — Thetford uses different numbering per product family. This table is the N3000 and N4000 absorption series (codes 1-13). The older Premium LCD line (N90-N180, built 2005-2012) has its own, different 1-14 table in which the same numbers mean other things, and the T2000 compressor fridges use a third scheme again. Model numbers are no help either: N90, N97, N100, N104, N109, N112 and N145 appear in both the Deluxe line and the Premium LCD line, so a bare model number cannot decide which table applies. Check which family your fridge belongs to before acting on a number.
Applies to
N3080 · N3090 · N3097 · N3100 · N3104 · N3108 · N3112 · N3115 · N3145 · N3150 · N3170 · N3175 · N4080 · N4090 · N4097 · N4100 · N4104 · N4108 · N4112 · N4141 · N4142 · N4145 · N4150 · N4170 · N4175
FAQ
What does Thetford Refrigerator code "Error code 13" mean?
The thermistor has failed and the control has switched itself to the Backup Operation System. The fridge keeps cooling, but blind: without a working temperature sensor it can no longer regulate to the setting you chose. How you read this code depends on the control panel. An LCD panel shows a spanner symbol with the number next to it. An LED+ panel shows nothing until you ask for it: while the display is blinking, hold all three buttons at once until it stops, and the cooling-level bars that then light up are a binary number — the five bars are worth 16, 8, 4, 2 and 1 from left to right, added together. And note Thetford's own warning: with no 12 V DC at the control board, no error code is shown at all.
How do I reset Thetford Refrigerator Error code 13?
Reconnect or replace the thermistor first, then switch the fridge off and on. Give it a full cooling cycle before judging: with Backup Operation the fridge runs to a fixed pattern, so temperatures behave differently until the sensor is back.
What is the most common cause of Error code 13 on a Thetford Refrigerator?
The most likely cause is thermistor unplugged or not seated in its connector.
Related · Thetford refrigerator
Flame detected when the gas should be off. The board senses a flame… Error code 2
The burner control module returns incorrect feedback. The ignition… Error code 3
Gas lockout: the burner failed to light within 30 seconds, so the board… Error code 4
The 12 V heating element is off when it should be on. The board is… Error code 5
The 12 V heating element is on when it should be off. The board sees DC…
Sources
- Troubleshooting — Absorption Refrigerator N3000 series — Error-code table 1-13, "Service mode LED" and "Service mode LCD" pages, per-code diagnostic flows (Thetford)
- Troubleshooting — Absorption Refrigerator N4000 — Version 05-2019 — identical error-code table 1-13 (Thetford)
- Fehlerbehebung — Absorber-Kühlschrank N3000 (deutsche Ausgabe) — Fehlercode-Tabelle 1-13, "Service Modus LED" mit Binärgewichten 16/8/4/2/1 (Thetford)
● Checked against 3 manufacturer documents · Last verified 2026-08-04 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual. How we verify