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Error Code P0032 is defined as HO2S (Heated Oxygen Sensor) Heater Control Circuit High, Bank 1, Sensor 1. This refers to a trouble with the oxygen sensor located at Bank 1 right in front of the catalytic converter.
Oxygen sensor 1 is also referred as air/fuel ratio sensor on some makes and vehicles. It works by detecting the level of oxygen that gets into the exhaust gas relevant to the outside air. The vehicle then adjusts its air/fuel ratio that goes into its engine. When gas temperature out of the exhaust is low, the sensor becomes less effective. This is why it comes with a heater, which is controlled and activated by the O2 sensor according to its readings. Thus, Error Code P0032 means heater circuit’s resistance is higher than it should be, or simply doesn’t fall into its predefined parameters. In some cases, resistance (signal voltage) level should be around 10 A or higher to trigger this error code.
Two conditions that may also cause this Error Code are:
- Most of the time, the circuit’s electrical resistance must be around 9 Ohms, and a 10% deviation can trigger the code.
- This can also be triggered when the PCM doesn’t detect any change in the O2 sensor reading for periods of above 8 seconds.
Aside from the activation of Check Engine light, this error code also comes with various symptoms like:
The PCM will read the O2 sensor heater circuit high and will set to failsafe mode until the ignition is cycled off.
Failsafe mode can result in various drive complaints, depending on the model of the vehicle.
Problems that come with failsafe mode will continue until the problem is solved.
Some of the drivability problems include:
- Loss of engine power
- Increased fuel consumption
- Lean running condition
- Emission of black smoke from the tail pipe
Usually, if this code is cleared and reset, then warning light will come to back to the OBD-II, this is because the Heater Oxygen Sensor for the bank 1, sensor 1 of the engine, is not sending the right data from the PCM, which may suggest damage, defects or bad wiring. It is however, quite rare for PCM to be damaged.
This error code may be caused by one or more of the following:
- Failed oxygen sensor heater
- Short in heater circuit sensor
- Broken connectors or wirings
- Damaged O2 sensor caused by road debris
- Defective O2 sensor
- Large leaks in the exhaust
- Bad quality fuel additives or aftermarket oil
- Low or excessive fuel pressure (you must also check for error codes related to fuel pressure)
- Loss of ground
- Unmetered air able to enter the engine
- Open circuits (caused by blown fuses)
How to Check
As with other related codes, you will need to thoroughly check all the connectors and wiring that lead to the sensor. If the engine is equipped with fuse and heater relay, you will have to check those as well. You will also need a digital volt ohm meter to check for the following:
- Check for 12 V at heater circuit feed, check the wiring connector by unplugging the sensor to get the measurement
- Check for continuity at the ground circuit
- Measure the heater circuit’s resistance; this is done by the sensor itself
- Measure the wiring’s voltage and the resistance
Always refer to the service manual for the specifications of volt and ohm measurements of the vehicle. Some Toyota models get this error code even when the resistance of the circuit is over 10A.
How to Fix
As with other error codes, you need a proper diagnosis to fix this code. The common fix for this error code however, is to replace the air/fuel (oxygen) sensor 1 on Bank 1.
Also, as we said earlier, this error code can be triggered by many different problems. But connection and wiring problems are most common, as they can be easily damaged by excessive heat.
Step 1: Turn off the engine and keep the key on. Then, use the voltmeter to check for 12V to the heater element of the battery feed.
Step 2: If there is no voltage present, then repair open or short in the 12V feed circuit. However, you should first determine if replacing any fuse blown from the short is really necessary.
Step 3: If the battery feed shows it’s correct, remove control circuit (ground) from the PCM wiring connector. Then, check the circuit for resistance.
Step 4: Repair the open in the circuit if there is infinite resistance.
Step 5: If the resistance is over 10A, and control circuit is in good shape, then it must be a problem with a bad Oxygen sensor. This means the sensor needs to be replaced.
Error Code P0032 is difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.
Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P0032.
It is also very important to retest the system after each step of fixing to ensure dependable repair.
Also, keep in mind that the original equipment of PCM is always recommended. Thus, should you need to replace damaged components, make sure you get it from your dealer, as most aftermarket sensors are lower in quality.
You can also check with your dealer if replacement for parts related to this error code falls under federal emission warranty.