P0140 means the ECU cannot detect any activity from the downstream oxygen sensor on Bank 1 (post-catalyst, Sensor 2). The sensor voltage is either flatlined or out of range. This usually points to a failed sensor, an open circuit in the wiring, or a connector that has come loose or corroded.
P0140 means the ECU cannot detect any activity from the downstream oxygen sensor on Bank 1 (post-catalyst, Sensor 2). The sensor voltage is either flatlined or out of range. This usually points to a failed sensor, an open circuit in the wiring, or a connector that has come loose or corroded.
P0140 est un code defaut lie a emissions, classe en gravite moderate. Lorsque le calculateur de ton vehicule detecte cette condition, il enregistre P0140 et allume le voyant moteur.
Si ton vehicule a declenche P0140, tu peux remarquer un ou plusieurs de ces symptomes :
Voici les causes les plus courantes de P0140, classees selon la probabilite qu'elles soient en cause :
En general oui, pour des trajets courts. Safe to drive short term. The downstream sensor reporting no activity does not affect fuel mixture, but the ECU loses its catalyst monitoring capability. Repair within a few weeks to maintain proper emissions diagnostics.
Suis ces etapes pour identifier la cause profonde de P0140 :
Les couts de reparation de P0140 varient selon la cause profonde et ton vehicule. Voici des estimations courantes :
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
P0140 se comporte differemment selon ton vehicule. Selectionne ta voiture ci-dessous pour des causes propres au modele, les problemes connus et des estimations de couts ajustees :
2006–2024
On N52 and N55, the downstream sensor connector clip is fragile and frequently breaks on older cars. A broken clip lets the connector vibrate loose, which presents as P0140 (no activity) even though the sensor itself is fine. Inspect and re-secure the connector before condemning the sensor. BMW OEM Bosch sensors 110–200 euros, aftermarket Bosch around 60–110 euros.
Couts estimes pour les proprietaires de BMW 3 Seriesajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a BMW
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2005–2024
EA888 TSI engines see P0140 most often from heater element burnout combined with oil-contaminated sensor element. Check the heater fuse first, then heater resistance at the sensor before buying parts. On older MK5/MK6 cars, the sensor harness can chafe against the heat shield, breaking the signal wire and producing P0140.
Couts estimes pour les proprietaires de Volkswagen Golfajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Volkswagen
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2006–2024
On the B7 and B8 A4 with 2.0 TFSI, the downstream sensor connector lives in a tight spot near the gearbox bellhousing and is prone to being knocked loose during clutch or gearbox work. Check for incomplete seating before replacing the sensor if P0140 appeared after recent work. Audi-OEM sensors 130–220 euros, aftermarket Bosch around 70–120 euros.
Couts estimes pour les proprietaires de Audi A4ajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Audi
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2007–2024
The W204 M271 1.8L Kompressor commonly triggers P0140 from heater element burnout around 130,000–150,000 km. The W205 OM651 diesel has the documented harness chafing point near the gearbox mount that can sever the signal wire, producing P0140. Mercedes-OEM Bosch sensors 130–220 euros, aftermarket Bosch around 70–120 euros.
Couts estimes pour les proprietaires de Mercedes C-Classajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Mercedes-Benz
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
Ces codes apparaissent souvent avec P0140 ou indiquent des problemes connexes :
The ECU expects the downstream O2 sensor signal to move within a defined range over time. If the voltage stays flat or out of range for the full monitor window, the ECU concludes the sensor has no activity and sets P0140. Most often the sensor itself has failed internally, or a wire has broken.
Yes, short term. The downstream sensor does not drive fuel mixture, so the car runs normally. Long term you lose catalytic converter monitoring, which means you may miss a developing converter problem until it is severe.
Unplug the sensor and measure heater resistance (typically 2–15 ohms). Plug it back in and back-probe the signal wire. With the engine warm and idling, a healthy downstream sensor reads around 0.6–0.8V steady. A flat reading at 0V or 5V with engine running points to an internal sensor failure.
Indirectly yes. If the heater fuse is blown, the sensor never reaches operating temperature and stays inactive, triggering P0140 alongside heater codes like P0141. Check the heater fuse first if you see both code types.
Branche un adaptateur OBD2 Bluetooth standard, scanne les codes et obtiens un diagnostic par IA avec niveaux de gravite et estimations des couts de reparation.
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