P0042 B1S3 Heated Oxygen Sensor Control Circuit

P0042 B1S3 Heated Oxygen Sensor Control Circuit

OBD-II DTC Datasheet

Oxygen Sensor Heater Control Circuit (Bank 2 Sensor 1)

What does this mean?

This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to OBD-II equipped vehicles, including but not limited to VW Volkswagen, Audi, Mazda, Ford, Chevy, etc. Although general, specific repair steps may differ depending on the brand / model.

In vehicles with fuel injection, heated oxygen sensors are used before and after the catalytic converters to determine the oxygen content in the exhaust system. This feedback is used to adjust the fuel system to maintain the proper 14.7: 1 air / fuel ratio.

Oxygen sensors use a heated loop to warm up the sensor for faster feedback. The oxygen sensor can use three or four wires depending on the vehicle, two are typically used for sensor feedback to the powertrain control module (PCM) / engine control module (ECM), and the other wires are for the heater to power the heated circuit. ... Three-wire sensors are typically grounded through the exhaust system, while four-wire sensors have a separate ground wire.

The P0042 code refers to the third sensor after the engine on bank 1, which is located on the side of the engine with cylinder # 1. The heater circuit can be powered or grounded from the PCM / ECM or other source that can be controlled by the PCM / ECM.

Note. Be careful not to work on a recently used exhaust system as it can become very hot.

symptoms

DTC P0042 symptoms include a Malfunction Indicator Lamp (MIL) illuminated. You probably won't notice any other symptoms associated with a heated circuit malfunction as it only works for a moment when the vehicle is first started. This sensor is also located after the catalytic converter, so it does not affect the input air / fuel ratio to the PCM / ECM; it is mainly used to test the efficiency of catalytic converters.

reasons

Possible causes of DTC P0042 may include:

• Open circuit inside the oxygen sensor or open power or ground wire to the oxygen sensor bank 1, No. 3
• The exhaust system grounding strap may be corroded or broken.
• PCM / ECM or oxygen sensor heater circuit wiring defective

Possible solutions

Inspect the oxygen sensor wiring for damage or loose wiring to the sensor.

Disconnect the oxygen sensor and with a digital volt-ohm meter (DVOM) set to ohms scale, check the resistance of the heater circuit, referring to the wiring diagram. There should be some resistance in the heater circuit inside the sensor, excessive resistance or exceeding the limit value will indicate an open in the heated part of the circuit, and the oxygen sensor must be replaced.

Check the ground wire at the connector and check the resistance between a well-known ground and the oxygen sensor connector.

Check the power supply wire on the connector with the DVOM set to constant voltage with the positive wire on the power supply wire and the negative wire on a well-known ground to verify that there is power to the oxygen sensor. If there is no power to the connector during the initial vehicle start (cold start), there may be a problem with the oxygen sensor power supply circuit or the PCM itself.

Related DTC discussions

• 03 Jeep Liberty P0042Hi, I have a 2003 Jeep Liberty Sport. 3.7 V6 Bought a pocket scanner. actron CP9125. I hooked it up to the jeep because the check engine light came on again and stayed on this time. I got the code P0042. H02S bank 1 Sen 3 Heater Circuit. Where is he in my jeep? I read that I should c ... 

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