P2AEF: Intake Air O2 Sensor Negative Current Control Circuit Open Bank 2

P2AEF indicates that the return line, or virtual ground, of the bank 2 intake oxygen sensor is open. Both cells of a wide-band element reference this lead, pin 2 (IPN/VM) on the Bosch LSU 4.9, which the ECM biases so current can flow both ways. Ford's 2012 summary describes the bank 2 exhaust analog P2254: if the sensor voltage settles inside a narrow band (1.45-1.55 V with the Bosch CJ125, 1.95-2.05 V with the Conti ATIC42) for 10 s, the return is judged open. Nothing comparable is published for an intake sensor, and no maker documents P2AEF. A second intake sensor exists only where every bank has a separate intake or EGR route. While the return is open, bank 2 EGR loses its feedback; drivers usually see only the lamp. P2AF0/P2AF1 are low/high, P2AEC the open pump lead, P2AE6 bank 1.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

• Check engine light on
• Usually no noticeable change in driveability

Most likely causes

• Return lead (pin 2) broken
• Return contact corroded or loose
• Internal break of the common electrode

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 P2AEF means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• A: Hybrid or air and fuel
• EF: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2AEF?

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 P2AEF?

The most common causes are: return lead (pin 2) broken; return contact corroded or loose; internal break of the common electrode.

Related codes

• P2AF0Intake Air O2 Sensor Negative Current Control Circuit Low Bank 2
• P2AF1Intake Air O2 Sensor Negative Current Control Circuit High Bank 2
• P2AECIntake Air O2 Sensor Pumping Current Circuit Open Bank 2
• P2AE6Intake Air O2 Sensor Negative Current Control Circuit Open Bank 1
• P2254O2 Sensor Negative Current Control Circuit/Open (Bank 2 Sensor 1)

Sources

• newtonnet.co.uk: fordobd2012
• bosch-motorsport.com: Data Sheet 69034379 Lambda Sensor LSU 4.9
• law.cornell.edu: 13 CCR 1968.2

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.