P2628 OBD-II Trouble Code: O2 Sensor Pumping Current Trim Circuit / High Bank 1 Sensor 1

P2628 Code Definition

The P2628 code is a generic powertrain code related to computer circuit output issues. This code appears when the oxygen sensor pumping current trim circuit for engine bank 1 has sent the engine control module (ECM) a voltage signal too high for the accepted variances. This code usually relates to the bank of the engine block with the number 1 cylinder, and sensor 1 is the upstream sensor, which is ahead of the catalytic converter.

The P2628 code is related to:

• P2626: O2 Sensor Pumping Current Trim Circuit/Open Bank 1 Sensor 1
• P2627: O2 Sensor Pumping Current Trim Circuit/Low Bank 1 Sensor 1
• P2629: O2 Sensor Pumping Current Trim Circuit/Open Bank 1 Sensor 1
• P2630: O2 Sensor Pumping Current Trim Circuit/Low Bank 1 Sensor 1
• P2631: O2 Sensor Pumping Current Trim Circuit/High Bank 2 Sensor 1
• P2195: O2 Sensor Signal Stuck Lean Bank 1 Sensor 1
• P2196: O2 Sensor Signal Stuck Rich Bank 1 Sensor 1

What the P2628 Code Means

If a P2628 code is stored, the ECM has detected a variation of 10% or higher than the accepted voltage levels. The sensor detects oxygen content in a vehicle's exhaust gas and sends the voltage information to the ECM, which controls fuel injection durations.

For proper engine function, 14:7 air/fuel ratio must be present. The ECM controls the fuel delivery, timing of the ignition, and the fuel injector pulse. It also receives signals from several sensors to help ensure proper fuel delivery and air/fuel ratios. The heated oxygen sensor helps detect oxygen levels in a vehicle’s exhaust system and measures if the engine is running lean or rich. The oxygen sensor features a heater that is warmed with an electrical voltage to help warm it up for quick measurements faster than simply through using the heat of the exhaust gases, thus decreasing emissions and the length of time for a vehicle to enter a closed-loop mode.

A P2628 code can also be stored if the when the engine is running in a closed loop and oxygen sensor readings remain constant for usually more than eight seconds.

What Causes the P2628 Code?

The P2628 code is caused by several potential problems, including:

• Damaged or defective oxygen sensor 1 in bank 1
• Damaged or defective electrical connector
• Damaged or faulty wiring
• Damaged or blown fuse
• Incorrect fuel pressure
• Damaged or defective hoses
• Possible vacuum leak
• Damaged or defective ECM (rare)

What are the Symptoms of the P2628 Code?

The symptoms of a P2628 code include:

• Warning or Check Engine Light illuminated
• A lean condition in the engine
• A rich condition on the engine
• Poor fuel efficiency
• Tailpipe may produce black smoke

How Does a Mechanic Diagnose the P2628 Code?

A mechanic will diagnose a P2628 code in a number of ways, including:

• Use an OBD-II scanner to check for a stored P2628 code
• Visually inspect the vehicle for any obvious signs of damage
• Check for any damaged or faulty wiring and connectors
• Check the wiring harnesses for damage from hot exhaust gas
• Check for any bent, damaged, or corroded pins
• Remove and inspect the oxygen sensor
• If sensor is not performing correctly, disconnect connector and test the sensor
• Use a digital volt/ohmmeter to test sensor function and volt readings
• Test voltage to sensor heater circuits, both power and ground
• Clear the code, test-drive the vehicle, and retest to see if the code reappears

Common Mistakes when Diagnosing the P2628 Code

One of the most common mistakes when diagnosing a P2628 code includes the replacement of oxygen sensors when the actual cause are lean or rich engine conditions. In addition, ensure the correct oxygen sensor is being replaced.

How Serious is the P2628 Code?

Because a vehicle with a P2628 code should operate normally, but may exhibit increased emissions and decreased fuel efficiency, this is not considered a serious issue, but it is still recommended that you have the code diagnosed and repaired sooner rather than later.

What Repairs can Fix the P2628 Code?

• Repair or replace damaged or faulty wiring and connectors
• Replace any damaged wiring harnesses or components
• Repair or, if necessary, replace the faulty or damaged oxygen sensor
• Repair or replace any bent pins
• Repair or replace any damaged circuits
• Repair or replace any damaged or leaking vacuum hoses
• Repair or replace the ECM (rare)

Need Help with a P2628 Code?

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