Error Code P2251: What It Means & What To Do?

<<See All OBD Codes

The code P2251 is an OBD-II general code. The engine control module (ECM) inspects the low current management of the O2 sensor heater circuit. If the current is unable to be managed and the voltage is unable to shift at the return wire, then the ECM recognizes this is an open circuit in the heater circuit sending for the O2 sensor heater circuit.

The front Oxygen Sensor, this is O2 Sensor 1, is situated in the exhaust manifold. It determines the quantity of oxygen in the exhaust gas in comparison to the outside air. The oxygen sensor 1, which is heated has a tune with a closed-end that is constructed of ceramic zirconia. The zirconia initiates voltage that is roughly from 1V in exorbitant settings to 0V in slimmer settings. The oxygen sensor 1 that is heated sends a signal to the Engine Control Module (ECM). The ECM repairs the injection pulse continuance to succeed in the wanted air-fuel ratio. The wanted air-fuel ratio happens close to the far-reaching shift from 1V to 0V.

What causes this problem with the 02 Sensor Negative Current Control Circuit/Open Bank 1 Sensor 1?

• The O2 sensor connected to bank 1 sensor 1 contains an open circuit in the heater circuit.
• A damaged wire or connector is found on the O2 sensor.
• An open wire is found in the power supply circuit from the ECM to the O2 sensor heater circuit.
• An open or short is found on the return signal wire leading back to the ECM.

1. Engine Control Module - The Engine Control Module (ECM) could fail if there is damage or corrosion that spreads to the interior wiring setting inside the injector wiring harness or the sensor wiring harness, which can lead to creating a short within the ECM, or corrosion can enter the ECM and stream through the wiring harness. This can happen even when being exposed with a diversity of elements surrounding the vehicle’s environment.
2. Oxygen Sensor - When you detect a bad oxygen sensor, your vehicle will run less effectively, and it can occasionally have a bad idle, irregular jerking at constant throttle, problems with hard starting, results in checking for the engine light to come on, and will result in high fuel consumption. Therefore, when oxygen sensor failure has been found, when the check engine light comes on and sets an O2 sensor code, the sensor has to be replaced. Replacing an oxygen sensor is a task that you can achieve yourself, only if the O2 sensor is not entirely festered into the pipe or catalytic converter, therefore saving you valuable time and money.
3. Exhaust Manifold - A problem with an exhaust manifold gasket is a compulsively loud engine.
   A defective exhaust manifold gasket will cause a leaking exhaust that will make a hissing or tapping sound that comes out of the engine. The sound might even be noticeable at a cold start or when speeding up. Engine performance problems are another recurrent symptom of a problem dealing with an exhaust manifold gasket. If the exhaust manifold gasket begins to fail, the exhaust leak will cause engine performance problems like a reduction in power, speed, and fuel efficiency. The performance reduction might be slight at first glance, but will get worse over duration of time if not properly attended to. A possible problem with the exhaust manifold gasket is a burning odor coming out of the engine bay. If the gasket is failing and leaking close to any plastic elements, or engine wiring, the heat coming out of the exhaust gases might result in the elements burning up. This might lead to a burning odor that comes out of the engine bay, which causes the elements to get in contact with rising heat. The odor might occasionally be assisted by vague smoke. Any kind of burning odors have to be inspected right away to ensure that they are not possibly a danger warning.
4. Oxygen Sensor Connector - Since this connector has an important job at inspecting fuel emissions, take regard that CEL lights up after doing a couple driving cycles with a broken O2 sensor. Having incorrect data that comes from the O2 sensor, the ECU will not run effectively, also a fuel level reduction is visible and evident in the fuel economy. A low oxygen sensor makes it difficult for the ECU to make adjustments for the needed quantity of fuel during the time of an unexpected speed up. This could occur when the O2 sensor runs constantly in an Open Loop Mode. Having failed to deliver the correct quantity of fuel towards the engine will result in visible gas odor coming out of the exhaust pipe. A defective oxygen sensor will rise up all fuel emissions that can cause a problem if you reside in a place that checks for smog, or tests vehicle emissions. It depends on the year and make of the vehicle that an ECU might not be able to make amends to this failure when idling. This could result in a bad idle or even a periodically failing engine when idling. This is normally a result of the incorrect quantity of fuel accessing every cylinder.

It is important to learn all about the symptoms of a problem, as this way you’ll have the skills to easily solve this problem. This is why our team has written out a few primary symptoms of OBD code P2251 as described below:

Common Symptoms

• The Check Engine Light is going to illuminate and the code will be set in the ECM memory as a defect.
• The ECM might experience control loss in the fuel control circuit for the O2 sensor and for bank 1 sensor 1.
• The ECM might enter failure management mode so it can control the fuel flowing to the engine.
• The engine fuel mileage is going to drop and the engine might experience a difference in fuel-associated symptoms.

There are a few methods that will help in being able to easily correct the OBD Code P2251:

• The after-treatment of exhaust/fuel injector is usually staged right into the diesel particulate filter or catalytic converter, and it is usually electronically in control by utilizing a well-committed after-treatment of exhaust/fuel injector controller that is utilized in connection with the PCM.
• When turning the input shaft, by way of the engine, the electromagnetic input/turbine speed sensor utilizes the spaces set between the splines to give voltage signal disruptions in the circuit.
• CAN is the short-term for Controller Area Network. The CAN stands for a communication bus that enables many microcontrollers to send readings to each other, while having no need for a host computer.
• Many tools will be instrumental in achieving the diagnosis of this code.

Do not hesitate to contact our team at Parts Avatar - Car Parts Online, as we are here to guide you! We have in stock upscale ECM, Oxygen Sensor, Exhaust Manifold, Oxygen Sensor Connector and even more to impress our customers.

It is important to diagnose this error code. We provide a few methods that a mechanic has to read through to diagnose the problem that activated this code P2251 in being stored:

• Scan and document the codes in the ECM and observe the freeze frame data for signs of failure.
• Measure the voltage sending to the O2 sensor on the heater circuit.
• Measure the resistance of the O2 sensor heater circuit located at the ECM and at the sensor, as well as checking to find out if they are right descriptions.
• Detect the harness for wires that are short or damaged.

Common Mistakes When Diagnosing the P2251 Code

The code P2251 is a failure that commonly occurs in the O2 sensor heater circuit and the O2 sensor might be relinquished as not able to be responsive for the exhaust O2 and result in the ECM switching off to failure mode. This might result in the vehicle to fail at testing for emissions and result in drive objections that relies on the vehicle producer.

• Making sure to clear the ECM memory codes prior to detecting the freeze frame data for the major failure error, so the failure might be multiplied and adjusted.
• To fail in clearing the ECM codes after fixing the codes.
• Having the O2 sensor replaced without identifying the failure in the heater circuit might mean an erratically shorted wire in the harness.