How is P2272 different from P2270?

They're the same fault on opposite banks. P2270 is the downstream sensor on Bank 1 stuck lean; P2272 is the downstream sensor on Bank 2 stuck lean. Both are emissions/catalyst-monitoring codes that rarely affect how the car drives.

Which side is Bank 2?

Bank 2 is the cylinder head that does not contain cylinder 1 on a V6, V8, or similar engine. Inline engines have only Bank 1 and never set P2272. Confirm which physical side is Bank 2 for your engine in a repair database before diagnosing.

Is P2272 worth fixing right away?

It won't leave you stranded, but it will fail an emissions test and can accompany a Bank 2 catalyst problem. Diagnose it before your next inspection — start with the sensor and a check for exhaust leaks near the rear Bank 2 sensor.

Could one problem set both P2270 and P2272?

It's possible but less common, since the downstream sensors are on separate banks and separate exhaust paths. A shared cause would usually be something systemic like a wiring harness or ground problem affecting both rear sensors, or a broad rich/lean condition that also shows upstream codes.

OBD-II trouble code

P2272: O2 Sensor Signal Stuck Lean (Bank 2, Sensor 2)

The downstream oxygen sensor on Bank 2 — behind the catalytic converter — is reporting a signal stuck toward lean. It's the Bank 2 mirror of P2270 and mainly an emissions code; the car almost always drives normally.

Quick facts

System: Powertrain
Category: Oxygen Sensor
Severity: Low severity
Drivable: Usually safe to drive short-term
Repair cost range: $150 – $400
DIY difficulty: Intermediate DIY

What does P2272 mean?

This code is the Bank 2 counterpart of P2270. The downstream oxygen (O2) sensor on Bank 2 sits behind that bank's catalytic converter and monitors catalyst efficiency rather than doing primary fuel control. Its signal should be relatively steady and mid-range on a healthy system because the catalyst buffers the oxygen swings.

P2272 sets when the Bank 2 downstream sensor signal stays biased or stuck toward the lean side — a low, flat voltage — instead of behaving the way the engine control module (ECM) expects. It's a rationality fault: the circuit is electrically fine, but the reading is stuck and no longer plausible.

"Bank 2" is the side of a V-configured engine that does not contain cylinder 1; inline engines have only Bank 1 and never set P2272. "Sensor 2" is the downstream sensor. Because this sensor does little or no fuel trimming, P2272 rarely affects driveability. The most common cause is an aged or contaminated downstream sensor; the next most likely is an exhaust leak near the rear Bank 2 sensor drawing in outside air that reads lean. Less commonly the reading is accurate and the exhaust or catalyst on that bank is the real issue.

Common causes

Aged or contaminated downstream Bank 2 oxygen sensor (most common)
Exhaust leak near the rear Bank 2 sensor letting in outside air that reads lean
Damaged, chafed, or corroded downstream sensor wiring or connector
Sensor heater degraded, slowing response
Moisture intrusion into the sensor connector
Genuine post-catalyst lean reading from a Bank 2 exhaust or catalyst problem (less common)

Symptoms

Check engine light is on
Almost never any driveability symptom
Failed emissions inspection
Possible companion catalyst code such as P0430
Slightly elevated tailpipe emissions in some cases

Diagnostic steps

1.Scan for all codes. A companion P0430 suggests inspecting the Bank 2 catalyst and exhaust rather than just the sensor.
2.Watch Bank 2 Sensor 2 voltage live and compare with Bank 1 Sensor 2. The downstream signal should be steady mid-range; with P2272 it sits low and flat.
3.Inspect the Bank 2 exhaust from the catalyst back for leaks, especially near the rear sensor bung.
4.Inspect the sensor connector and wiring for corrosion, chafing, or moisture.
5.Check the sensor heater circuit if the signal is slow to come alive after start-up.
6.If the exhaust is tight and wiring is good, replace the downstream Bank 2 sensor.

Repair cost

$150 – $400

Downstream oxygen sensor replacement runs about $150 to $400 in parts and labor, with the sensor typically $40 to $150. Access to the rear Bank 2 sensor varies by vehicle. Repairing a nearby exhaust leak adds $100 to $400 depending on what needs welding or replacing.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with oxygen sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.