Code P0130: lambda sensor circuit (bank 1, sensor 1)

Both affect the same lambda sensor (the front one on bank 1), but different circuits. P0130 points to the circuit of the sensor itself, the one that generates and transmits the oxygen signal, and is investigated by looking at that signal in the live data and its wiring. P0135 points to its heater circuit, the built-in element that brings it up to working temperature after starting; without a heater, a sensor would take several minutes to become useful.^{[2][3][4][21][22]}

The sources do not fully agree. Rick's Free Auto Repair Advice says the engine can keep running almost normally and Carista rates it as medium severity; Autodoc Club, on the other hand, recommends repairing it as soon as possible and warns that it can make starting difficult and damage the engine. The prudent course is to have it checked soon at a garage and not to keep using the car with the warning light on.^[1][3][4]

Not necessarily. Wiring and connector problems explain, according to Rick's Free Auto Repair Advice, a surprising number of cases, and exhaust leaks, contamination of the sensor tip or engine faults that alter the mixture can also cause the code. The usual fix is to replace the sensor when it does not switch properly or is contaminated, but only after ruling out everything else.^[1][3][4]

"Bank 1" is the side of the engine where cylinder 1 is, and "sensor 1" is the front lambda sensor, the one in the exhaust before the catalytic converter (upstream).^[2][3]

Yes as far as the definition goes: codes starting with P0 are generic OBD-II codes. However, the sources do not describe in the same way how the ECU sets it, so it is best to look at the sensor's live data and not rely on the code alone.^[1][4][5]

All five point to the front lambda sensor circuit of bank 1 and only the type of fault changes. P0130 is the general circuit fault. P0131 indicates a persistently low voltage: according to Carista, a faulty sensor or a genuinely lean mixture, for example from intake air leaks or low fuel pressure. P0132, a persistently high voltage: a sensor with an internal short, a short to voltage in the signal wire or a genuinely rich mixture. P0133, a slow response: an aged or contaminated sensor that no longer switches as quickly as needed. P0134, no activity detected: the sensor does not switch, because of a faulty sensor, a disconnected or broken wire, a corroded connector or a heater that does not let it warm up. Ross-Tech, for VAG group cars, recommends in every case checking the wiring and connectors before testing or replacing the sensor.^{[8][9][12][15][16][19][20]}

If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.^[23]