2010 Prius P2237 O2 Sensor Code

FYI - Here's some information to keep in mind if you start to troubleshoot the code.
It's related to other Toyota cars with the same code.

 

There is no TSB for Prius.

Like the article said "Test the devices in question" if they are good then it could be something else.

The next thing to check is the wiring. That problem has been seen on other Toyota cars with the same code.

More than likely the mechanic will want to replace the o2 sensor.
If the light comes back after you replace it you can point to this article as the next thing to look at.

Someone on prius chat with an earlier model had the same issue trying to fix that code and could not get it fixed after the o2 sensor was replaced many times. Search this website for the code and read his ordeal.

 

Here are things to look at under Possible causes:
It's all I got, hope it helps.
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P2237 Toyota Oxygen (O2) Sensor Positive Current Control Circuit / Open (Bank 1 – Sensor 1)
Possible causes
- Faulty Heated Oxygen Sensor Bank 1 Sensor 1
- Heated Oxygen Sensor Bank 1 Sensor 1 harness is open or shorted
- Heated Oxygen Sensor Bank 1 Sensor 1 circuit poor electrical connection
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P2237 Toyota Description
The linear O2 sensor is mounted on the front side of the Catalytic Converter (warm-up catalytic converter) or in the front exhaust pipe. It detects a wide range of air/fuel ratios in the exhaust gas from the rich to lean regions. This linear O2 sensor produces a current that corresponds to a specific air/fuel ratio. The Engine Control Module (ECM) monitors this signal and determines whether the air/fuel mixture is rich or lean. The ECM constantly monitors the linear O2 sensor and increases or decreases the fuel injection duration using this signal. This is called closed-loop fuel control operation.

 

The DTC codes that I have specifies the Air-Fuel Ratio Sensor 1 which is the one upstream of the Cat Converter.

P2237
Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)
- Open in air fuel ratio sensor (sensor 1) circuit
- Air fuel ratio sensor (sensor 1)
- ECM

There are a variety of codes for the A/F Sensor for a variety of problems. This one is specific with an open circuit. It sounds like replacing the sensor would be a good first step. If you can disconnect the connector and test the sensor for open circuit this would help determine if it is the sensor, the connector or the cable.

 

The Repair Manual indicates an open circuit between terminals A1A+ and A1A- which is the sensor signal to the ECU.

P2237 (Air Fuel Ratio Sensor Open Circuit Between A1A+ and A1A-)


Air fuel ratio sensor admittance Below 0.002 1/Ω

 

you found your culprit....

 

The sensor would seem to be the most likely candidate. A loose connection or broken wire could also cause the open circuit. So there are multiple possibilities here.

If it were mine, I would disconnect the electrical plug to the sensor and check the resistance between the A1A+ and A1A- terminals. If I read an open circuit with a multimeter then that would indicate the sensor is faulty and I would replace the sensor. If the sensor read something greater than 0.0021 ohms then this would eliminate the sensor and I would begin checking the circuit connector and wiring back to the ECU module.

The dealer tech should follow the Repair Manual procedure which includes testing the resistance of the circuit. Most dealers that I have dealt with in the past prefer to replace parts first and then troubleshoot the problem further if this does not resolve the problem. You still have to pay for the replacement part even though that does not fix the problem. Most electrical parts are non-returnable.

 

Different vehicle, but this video may put you on the right track:

 

Nice video.