P0032 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 1 Sensor 1)

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P0032 trouble code definition

P0032 is the code for HO2S Heater Control Circuit High (Bank 1 Sensor 1)

What the P0032 code means

P0032 sends sensor data for the engine to operate properly as the engine exhaust should have a specific air-fuel ratio of 14.7 to 1 as detected by the heated oxygen sensors (HO2S) which defines the oxygen content of the vehicle exhaust. This code is for the HO2S in front of the catalytic converter. This data is then sent to the engine control module (ECM) to adjust the amount of fuel delivered to the engine.

An HO2S is heated to insure very quick response to send data to the ECM closed loop system which helps control exhaust emissions during startup, when the engine is cold or in warm up mode. If the resistance on the heater circuit is above 10A it is out of range.

What causes the P0032 code?

Generally, if the code is cleared and reset, then the engine warning light comes on the OBD-II code comes back, the HO2S sensor for the engine bank 1 and sensor 1 is not sending the correct data to the ECM and may be damaged, defective, or have bad wiring. It is quite rare if the ECM is bad.

What are the symptoms of the P0032 code?

  • The Check Engine Light will come on.

  • The ECM detects the O2 sensor heater circuit high and will enter failsafe mode until the ignition is cycled off.

  • The failsafe mode can cause various drive complaints depending on the vehicle model, manufacturer, and the ECM programming.

  • This failsafe mode will continue until the problem is repaired or the problem is not happening when the vehicle is started.

  • Some of the common drive problems you may have are hesitation, runs rough, or low power.

How does a mechanic diagnose the P0032 code?

  • P0032 is diagnosed with an OBD-II scanner. The mechanic can reset the OBD-II code and test drive the vehicle to see if the code returns.

  • If it comes back on, the mechanic should check both power and ground to the sensor including inspecting the wiring, connectors, and sensor.

  • Many of the problems on this code are wiring related due to the heat of the exhaust damaging it due to proximity to the exhaust system..

Common mistakes when diagnosing the P0032 code

  • Do not immediately decide to replace the HO2S before checking the all of the related wiring and the connector closely.

  • The mechanic must ensure there is 12 volts to the sensor and that the ground is good.

  • Inspect both sides of the connector wiring to insure the connector is good and not damaged.

How serious is the P0032 code?

The P0032 code will usually be preceded by the engine warning light coming on the vehicle’s dash while it is in operation. The vehicle can still be driven normally, but it should be professionally diagnosed as soon as possible to prevent problems like the sensor loop failing, excessive fuel consumption, poor operation, or potential damage to other components.

Often times, if the engine warning light came on immediately at start up, the OBD-II system can be reset and the vehicle will operate normally.

What repairs can fix the P0032 code?

The most common repairs to address the P0032 code are as follows:

  • Have a certified technician verify the code with a scanner. Reset the fault codes and then perform a road test.

  • If the P0032 code returns, then follow the test procedure.

  • It can have several problems, but wiring being damaged by excessive heat from the exhaust is most common. Make certain the wiring is in good condition and has proper voltage and ground to the sensor before replacing the sensor.

  • Check the resistance on the heater circuit to determine if it is over 10A.

Test procedure:

  • With key on and the engine off, use a voltmeter to check for 12+ volts fused battery feed to the heater element.

  • If there is no voltage present, repair open or short in the 12 volt feed circuit but first determine if it is necessary to replace any fuse blown from the short.

  • If the battery feed is correct, remove the ground (control) circuit from the ECM wiring connector and check for resistance on the circuit.

  • If there is infinite resistance, repair the open in the circuit.

  • If the resistance is above 10A and the control circuit is good, suspect a bad O2 sensor. Replace the sensor and recheck.

I have found that this is not a simple diagnosis or repair as there are many potential problems with this P0032 code. I had this code on a BMW 328i and everything looked good, so I replaced the sensor 1 in front of the catalytic converter. I reset the code and it immediately the engine warning light came on which meant there was something else wrong.

Sensor 1 is very hard to get to and because everything was very tight in that area around the exhaust, I could not see that the wiring on the body loom was damaged and melted to the exhaust pipe near the firewall. I took over an hour to remove the exhaust and another half hour to repair the wiring loom which I fortunately knew required special wire, not normal electrical wire, then another hour to put everything back properly.

I also put in several tie wraps to make certain the wiring was away from the exhaust. This was a good lesson to check voltages and grounds before putting in a new sensor.

Additional comments for consideration regarding the P0032 code

Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train. If the engine warning light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.

Need help with a P0032 code?

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