P0061 Heated Oxygen Sensor Heater (HO2S) Resistance Sensor Bank 2 Sensor 3
Content
P0061 Heated Oxygen Sensor Heater (HO2S) Resistance Sensor Bank 2 Sensor 3
OBD-II DTC Datasheet
Oxygen sensor heater resistance (block 2, sensor 2)
What does this mean?
This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to all 1996 vehicles (Chevrolet, Ford, GMC, Mazda, Pontiac, Isuzu, etc.). Although general in nature, the specific repair steps may differ depending on the brand / model.
In my personal experience, a stored code P0061 means that the powertrain control module (PCM) has detected a malfunction in the heater circuit of the downstream (or pre-catalytic converter) oxygen (O2) sensor for the first row of engines. Bank 2 indicates that the malfunction concerns an engine group in which cylinder number one is missing. Sensor 3 indicates that the problem is with the lower sensor.
A zirconia sensing element protected by a vented steel housing is the heart of your typical O2 sensor. The sensing element connects to the wires in the platinum electrode O2 sensor wiring harness. The data from the O2 sensor is sent to the PCM via the Controller Area Network (CAN). This data contains information about the percentage of oxygen particles in the engine exhaust compared to the oxygen content in the ambient air. This data is used by the PCM to calculate fuel delivery and ignition timing. The PCM uses battery voltage as a means to preheat the O2 sensor under cold start conditions. The O2 sensor signal circuits are complemented by a circuit designed to preheat the sensor. The heater circuit typically consists of a battery voltage wire (12.6 V minimum) and a system ground wire. The PCM takes action to supply battery voltage to the O2 sensor heater when the engine coolant temperature is low. This usually happens until the PCM goes into closed loop mode. Voltage is supplied through the PCM, sometimes by relays and / or fuses. The circuit is energized when the ignition key is turned on under cold start conditions. The PCM is programmed to de-energize the O2 heater circuit as soon as the engine reaches normal operating temperature.
When the PCM detects an O2 sensor heater circuit resistance level that exceeds the programmed limits; P0061 will be stored and a Malfunction Indicator Light (MIL) may illuminate. Some vehicles may require multiple ignition cycles (on failure) to illuminate the warning light. If this applies to your vehicle, you will need to use OBD-II Ready Mode to ensure your repair was successful. After repairs, drive the vehicle until the PCM enters readiness mode or the code is cleared.
Severity and symptoms
When a P0061 code is stored it should be considered serious because it means the upper O2 sensor heater is not working. Symptoms of this engine code may include:
- Delayed start due to lean cold start
- Reduced fuel efficiency
- Black exhaust smoke due to rich cold start state
- Other associated DTCs may also be stored.
reasons
Possible causes of DTC P0061 may include:
- Burnt, broken, or disconnected wiring and / or connectors
- Defective O2 sensor
- Blown fuse or blown fuse
- Defective engine control relay
Possible solutions
A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.
While trying to diagnose the P0061 code, I got access to a diagnostic scanner, a digital volt ohm meter (DVOM), and a trusted source of vehicle information like All Data DIY.
I would probably start by visually inspecting the system's wiring harnesses and connectors. I would pay special attention to harnesses that are routed near hot exhaust pipes and manifolds, as well as those that are routed near sharp edges, such as those found on the exhaust shields.
I could then proceed by using the DVOM to test all system fuses and fuses. Qualified technicians will check these components while they are under load because unloaded fuses may appear to be OK; will then crash on boot. You can efficiently load this circuit by activating the O2 sensor heater / s.
My next step is to retrieve all stored DTCs and freeze frame data. This can be done by connecting the scanner to the vehicle's diagnostic port. I am recording this information as it may be helpful if P0061 turns out to be intermittent. Now I would clear the codes and test drive the vehicle to see if the P0061 resets immediately.
When the engine is cool enough to activate the O2 sensor heater and the code is cleared, observe the O2 sensor heater input using the scanner data stream. You may want to narrow the display of the data stream to include only the relevant data, as this will result in a faster data response. If the engine is in the correct temperature range, the O2 sensor heater voltage should be about the same as the battery voltage. If a resistance problem causes the O2 sensor heater voltage to differ from the battery voltage, P0061 will be stored.
You can connect the DVOM test leads to the sensor ground and the battery voltage signal wires to monitor real-time data from the O2 sensor heater circuit. Check the resistance of the O2 sensor using the DVOM. Keep in mind that all related controllers must be turned off before testing the system loop resistance with the DVOM.
Additional diagnostic tips and notes:
- The O2 sensor heater circuit must be energized when the engine temperature is below normal operating temperature.
- If blown fuses are found, suspect that the O2 heater circuit in question is shorted to ground.
Related DTC discussions
- There are currently no related topics in our forums. Post a new topic on the forum now.
Need more help with your p0061 code?
If you still need help with DTC P0061, post a question in the comments below this article.
NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.
