P2629: O2 Sensor Pumping Current Trim Circuit/Open (Bank 2 Sensor 1)

P2629 is the bank 2 counterpart of P2626 and only exists on V or boxer engines with two front wide-band probes. The module finds the trim branch of that probe interrupted. GM's 2023 table 23OBDG07 calculates the parallel resistance between the probe's APE and MES pins and fails values above 240 ohms as an open compensation resistor, two trips. VW's Touareg V6 and VR6 data book of 2014 uses a probe signal above 4.81 V; Ford checks both banks during deceleration fuel cut for a pure-air reading. Mercedes-Benz bulletin LI49.00-P-054888 (2014) for M278 and M157 V8s blames a damaged probe heater and calls for both upstream probes plus new engine software; Ford's EcoBoost TSB 17-2124 also covers the left-side probe. Bank 2 low and high are P2630 and P2631.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines. Sensor 1 is the oxygen sensor before the catalytic converter.

Symptoms

• Check engine light
• Bank 2 fuel control without wide-band feedback
• Possibly further bank 2 fuel trim codes

Most likely causes

• Bank 2 front probe faulty, including heater damage (Mercedes M278/M157)
• Open trim wire or loose terminal at the bank 2 probe connector
• Outdated engine software (update called for together with new probes)

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the wiring and connector of the sensor indicated
2. Check the continuity of the wire between the component and the control module.
3. Look for exhaust leaks
4. Check the signal in live data with the engine warm
5. Check the fuse and the heater resistance if the code mentions it
6. Replace the sensor if it has power and does not respond

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P2629 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 6: Control modules and outputs
• 29: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2629?

Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.

What causes code P2629?

The most common causes are: bank 2 front probe faulty, including heater damage (Mercedes M278/M157); open trim wire or loose terminal at the bank 2 probe connector; outdated engine software (update called for together with new probes).

Related codes

• P2626O2 Sensor Pumping Current Trim Circuit/Open (Bank 1 Sensor 1)
• P2630O2 Sensor Pumping Current Trim Circuit Low (Bank 2 Sensor 1)
• P2631O2 Sensor Pumping Current Trim Circuit High (Bank 2 Sensor 1)
• P2240O2 Sensor Positive Current Control Circuit/Open (Bank 2 Sensor 1)
• P2247O2 Sensor Reference Voltage Circuit/Open (Bank 2 Sensor 1)
• P2197O2 Sensor Signal Biased/Stuck Lean (Bank 2, Sensor 1)
• P0150O2 Sensor Circuit Bank 2 Sensor 1

Sources

• gsi.ext.gm.com: 23OBDG07
• static.nhtsa.gov: MC 10074008 2280
• newtonnet.co.uk: fordobd2012
• static.nhtsa.gov: MC 10136021 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.