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CoolingGeneric OBD-II codeUrgency: Garage soon

P0115 on Citroën: causes and affected engines

P0115 means: engine coolant temperature circuit (ECT sensor): malfunction.[1][2] Citroën has 4 documented faults that can trigger it, across 4 engines: 1.4/1.6 VTi, 1.6 THP, 1.0 VVT-i and 1.4 and 1.6 TU3/TU5. Only a diagnosis can confirm the cause on your car.

Documented faults
4
that can trigger it
Engines
4
used by Citroën, with at least one of them
Citroën models
11
with at least one of these faults
Urgency
Garage soon

11 sourcesHow we work

Documented faults in Citroën engines that can trigger P0115

Grouped by engine or model, from most to least important. These are faults with the thermostat and cooling system: not all of them will necessarily set the code, and only a diagnosis confirms the cause on your car.

Common causes of P0115 on any make

From most to least likely, according to the sources.

  1. 1Faulty coolant temperature sensor: this is the first cause cited by Autodoc and CarParts.[1][3][4][5][6]
  2. 2Sensor wiring and connectors in poor condition: damaged, chafed or corroded wires, loose or dirty connectors, water in the connector, a short circuit in the signal wire or an interrupted earth circuit.[1][3][4][6]
  3. 3Cooling system problems that distort the reading: low coolant level, air in the system, a faulty thermostat or engine overheating.[1][3][6]
  4. 4Faulty ECU (ECU/PCM): this is the least likely cause.[1][3]

What to check first

The first diagnostic steps, from the most likely and cheapest to check to the most expensive.

  1. 1Read the code and the live data with a diagnostic scan tool: the coolant temperature should rise consistently as the engine warms up. With the engine switched off for several hours, the coolant, oil and intake air temperatures should match to within about 5 °C at most; if one sensor deviates by more than 10 °C, it is the suspect. A disconnected sensor usually shows up on the scan tool as −40 °C.[4][6][7]
  2. 2Check the coolant level with the engine cold and make sure there is no air in the system. This is the cheapest check and can also distort the reading.[1][3][6]
  3. 3Inspect the sensor connector and wiring: corroded terminals, water in the connector, chafed wires. Wiggle the wiring loom at several points and in several directions while watching the reading to locate intermittent breaks or short circuits.[4][6]
Full guide to P0115: symptoms, diagnosis and whether you can drive

Frequently asked questions

Which Citroën engines have faults that can trigger P0115?

1.4/1.6 VTi (1 fault), 1.6 THP (1 fault), 1.0 VVT-i (1 fault) and 1.4 and 1.6 TU3/TU5 (1 fault). Each fault has its own page with the affected years and versions, the symptoms and the repair cost.

What does code P0115 mean on a Citroën?

Engine coolant temperature circuit (ECT sensor): malfunction. The engine ECU has detected a fault in the engine coolant temperature (ECT) sensor circuit, the part that tells it how hot the engine is. It uses that data to adjust fuelling, ignition and the switching on of the radiator fans. It is an NTC sensor, whose resistance drops as it warms up, and according to the sources the code is set by erratic signals, abnormal voltage or an open or shorted circuit. It is a generic OBD-II code: it means the same on a Citroën as on any other make.[1][2][3][5][6][8]

Can I keep driving with P0115?

Garage soon. The sources do not fully agree. Autodoc allows short trips with P0115, P0116 and P0117, although it does not recommend it for P0115, and asks for them to be repaired soon: for P0116 it adds that you must stop immediately if signs of overheating appear, and for P0117 it explains that the ECU switches to emergency values, with higher consumption and a risk of engine damage. KFZ Dietrich accepts short trips to the workshop as long as the warning light is not flashing, and requires immediate repair if it flashes or there is a loss of power or limp mode. CarParts, on the other hand, advises for P0117 to stop driving and go to a workshop as soon as the code appears. On the Saab 9-3, the expected effect is that the fans run non-stop.[1][4][7][9][10][11]

Sources

Every fact on this page links to its source. If you find an error, let us know.

  1. Código OBD2 P0115: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 4 October 2026 · in Spanish
  2. P0115 — Engine Coolant Temperature Circuit MalfunctionThe Automotive Technician (TaT) · Technical documentation · consulted 4 October 2026
  3. P0115 Code: Engine Coolant Temperature Sensor 1 CircuitCarParts.com · Technical documentation · consulted 4 October 2026
  4. Saab 9-3 (9400) 2001, Trionic T7: P0115 Engine Coolant Temperature Circuit. Performance Problem (copia del manual de taller de Saab)Saab Workshop Information System (WIS Online) · Technical documentation · consulted 4 October 2026
  5. Checking the coolant temperature sensor – symptoms, cause of failure and troubleshootingHELLA Tech World · Manufacturer · consulted 4 October 2026
  6. Engine coolant temperature sensor: how it works, symptoms, problems, testingSamarins.com · Technical documentation · published 18 July 2021 · consulted 4 October 2026
  7. P0117 vs. P0118: ECT-Sensor Kurzschluss und KabelbruchKFZ Dietrich (Kfz-Meisterbetrieb) · Other source · published 4 August 2026 · consulted 4 October 2026 · in German
  8. Sensor de temperatura del refrigerante: función, probar, síntomasAutodoc Club · Technical documentation · published 22 March 2021 · consulted 4 October 2026 · in Spanish
  9. Código de avería P0116 - guía paso a paso para su diagnóstico y resoluciónAutodoc Club · Technical documentation · consulted 4 October 2026 · in Spanish
  10. Código OBD2 P0117: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 4 October 2026 · in Spanish
  11. P0117 Code: Engine Coolant Temperature Sensor 1 Circuit LowCarParts.com · Technical documentation · consulted 4 October 2026