P0141: Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

Error code P0141 indicates a recorded malfunction in the oxygen sensor heater circuit (Bank 1 Sensor 2)

P0141 — a malfunction of the oxygen sensor heater downstream of the catalytic converter! During diagnostics, the computer displays the following message: "P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)". This error is very similar to the analogue P0135, which indicates a failure of the heater in the first lambda probe (upstream of the catalyst).

Distinctive features of a car with a stored P0141 error include potential RPM fluctuation during a cold engine start and the ECU switching to limp mode, which may cause increased fuel consumption.

The "Check Engine" light on the dashboard usually illuminates upon the second occurrence of the B1S2 heater fault. The engine controller diagnoses the circuit based on the heating element's resistance. Nominal resistance varies depending on the car make and the sensor itself, but is usually within the range of 2–15 Ohms (at room temperature).

Causes of Error P0141

The location in the connector block where contact with the lambda probe is most often lost

There are only a few possible causes that could signal the controller to set error code P0141:

1. Loss of contact in the lambda probe power connector (oxidation, open circuit);
2. Burnout of the heating coil inside the oxygen sensor;
3. Installation of a different type of sensor (with incompatible resistance).

Therefore, if the goal is to get rid of the dashboard light reminding you of a problem with the post-cat oxygen sensor, troubleshooting should start with checking the condition of the contacts and the integrity of the filament. It is important to understand: since this is an electrical problem (heater circuit), no amount of mechanical cleaning of the sensor itself will resolve error P0141.

Inspection and Troubleshooting

Lambda probe installation location (view from the inspection pit)

Many people immediately replace the sensor at the slightest suspicion, but if you are carrying out a DIY repair, you should perform an instrument check first.

You will need an inspection pit, as the second oxygen sensor is located downstream of the catalytic converter. Disconnect the power plug and inspect the contacts for oxidation or corrosion. Also check the wires leading from the connector for breaks. Next, use a multimeter in ohmmeter mode to measure the resistance of the lambda heater winding. To check, identify two wires of the same colour (usually two white or two black ones).

If the check reveals an open circuit inside the lambda, replace the sensor with a new one. There is a nuance here: car owners often install a universal sensor, the heater resistance of which may differ from the standard one, causing the error to persist.

If the check shows that the heater resistance is normal and the wiring is intact, clear the error from the ECU memory and check the condition of the connectors at the control unit end. In rare cases, the cause may be a fault in the ECU itself.