Fix P2626: Mechanic’s solutions that WORKED

The P2626 code indicates a problem with the oxygen (O2) sensor pumping current trim circuit for bank 1, sensor 1. This sensor is crucial for monitoring the oxygen levels in the exhaust to adjust the fuel mixture accordingly. An issue here can lead to improper fuel mixture adjustments, affecting the vehicle’s fuel efficiency and emissions output. Addressing this issue is vital for maintaining optimal engine performance and ensuring your vehicle meets emission standards.

P2626 quick overview

Meaning	P2626: O2 Sensor Pumping Current Trim Circuit/Open Bank 1 Sensor 1
Is it serious?	Yes, it can impact fuel efficiency, increase emissions, and potentially lead to further engine performance issues.
Possible causes	– Faulty O2 sensor – Wiring or connector issues related to the O2 sensor – Problems with the engine control module (ECM) or its software – Exhaust leaks
How to diagnose?	Inspect the O2 sensor and its connectors for damage or corrosion Check the wiring for breaks, shorts, or poor connections Test the O2 sensor operation using a scan tool or multimeter Examine the exhaust system for leaks Ensure ECM software is up to date and reset adaptives as necessary

How to fix P2626 – learn from mechanics

I looked into P2626 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Dodge

Vehicle Information 2007 Dodge Sprinter 2500 3.0L

Issue + Repair History

• Cannot clear code P2626.
• Three regeneration processes and a cleaning with Liqui Moly performed, but code persists.
• Readings KOEO for pressure sensors: Baro and manifold air pressure at 986 hPa, exhaust back pressure sensor at 992 hPa.

Other OBD2 Codes + Test Results

• P2626

Mechanic Suggestions

• Use a scan tool that can perform a DPF reset/adaptation to clear the soot load.
• Check differential pressure sensor readings.
• Inspect hoses off the DPF for cracks or breaks, and blow air through them to ensure they are not plugged.
• Consider checking the B1S1 O2 sensor.
• Ensure adaptives are reset.

Final Fix

• Reset the particulate filter adaptation, which went from 22 to 0, then cleared code P2626.

Case #2: Ford

Vehicle Information 2014 Ford Focus SE 2.0L

Issue + Repair History

• Code P2626 persists despite multiple attempts to resolve.
• Replaced O2 sensor three times.
• Replaced the computer.
• Rewired from the O2 sensor connector to the PCM.
• Code P2626 continues to reappear.

Other OBD2 Codes + Test Results

• P2626 – Bank 1 sensor 1 current trim circuit open

Mechanic Suggestions

• Check the wideband AFR sensor.
• Verify the use of an OE sensor.
• Voltage drop test the powers and grounds at the PCM and drag test the sensor terminals at the PCM.
• Understand the function of the resistor in the Universal Heated Oxygen Sensor (HO2S) connector and its impact on the PCM’s readings.
• OHM the internal current trim resistor in the universal heated O2 sensor.
• Check for broken or pinched wires and repair any open circuits.
• Check the connector to the PCM for any issues.
• Consider resetting Keep Alive Memory after sensor replacement.

Final Fix

• Discovered a problem in the bank 1 O2 sensor harness connector with only 2 strands of wire in the crimp. Installed OE connector to resolve the issue.

Case #3:

ehicle Information 2006 Hyundai Elantra GLS 2.0L

Issue + Repair History

• Code P2626 persists despite initial troubleshooting.
• Ohmed O2 pin 1 and pin 41 on PCM per Mitchell, connection seemed okay.
• MIL is off and no pending code, suggesting a historical code.
• Replaced the O2 sensor with 6 wires as suggested by Larry, Steve, Bartlomiej, and Tim.
• The replaced sensor was stuck at 2.50 volts, idle, or higher RPM.

Other OBD2 Codes + Test Results

• P2626 – O2 Pumping Current trim circuit/open b1s1

Mechanic Suggestions

• Follow Hyundai TSB # 03-36-014-01 for further testing.
• Replace the air fuel sensor, ensuring it’s OEM.
• Replace upper O2 sensor, preferably OEM.
• Wide-band O2 sensors use current, not voltage, as a parameter. The PCM calculates the amount of rich or lean by the amount of current it has to ‘pump in or out’ of the cell internally in the sensor.

Final Fix

• Replacing the O2 sensor, ensuring it’s OEM, resolved the issue.

Diagnostic Step	Brief Explanation
Reset the particulate filter adaptation and clear codes	Specifically addresses diesel particulate filter (DPF) related issues in diesel engines
Inspect and replace the O2 sensor with an OEM part	Ensures accurate oxygen level readings are being sent to the ECM
Check and repair wiring and connectors	Fixes potential electrical issues causing the circuit malfunction
Update ECM software and reset adaptives	Corrects any software-related issues affecting sensor operation
Perform voltage drop test on powers and grounds at the PCM	Identifies any electrical issues in the circuit between the O2 sensor and ECM
Inspect the exhaust system for leaks	Ensures accurate sensor readings by preventing outside air from entering the exhaust system

In each service case, resolving the P2626 issue involved thorough inspection and specific actions tailored to the vehicle’s needs, from resetting adaptations in a Dodge Sprinter to repairing a wiring connector in a Ford Focus, and ensuring the use of OEM parts for a Hyundai Elantra. These examples underscore the importance of accurate diagnostics and the use of proper parts and procedures to fix the underlying issue effectively.