P2251Fuel & Air Metering

O2 Sensor Negative Current Control Circuit Open Bank 1 Sensor 1

P2251 means the negative current control circuit of the air-fuel ratio sensor on Bank 1 Sensor 1 is open. This corrupts the wideband signal, usually from a failed sensor or wiring fault.

🚗 Yes, short-term, but expect an emissions test failure.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Failed air-fuel ratio sensor$80-$350

50%

The negative pump cell circuit fails open.

#2Open in wiring$50-$300

30%

A break in the negative current control circuit.

#3Connector corrosion$50-$200

15%

Poor contact opens the circuit.

#4ECM fault$300-$1000

Rarely, the module driver fails.

🩺 Common Symptoms

Check engine light
Failed emissions test
Rough running
Poor fuel economy

💰 Repair Cost: DIY vs Shop

DIY Cost

$80-$350

Shop Cost

$200-$500

📋 Free OBD2 Code Cheat Sheet

The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.

🔧 How to Diagnose P2251

1Inspect the sensor connector and wiring

2Check for opens in the negative control circuit

3Review sensor live data

4Replace the air-fuel ratio sensor if confirmed

❓ Frequently Asked Questions

Can I drive with P2251?

Short-term yes, but fuel control and emissions are affected.

How much to fix P2251?

Usually $200-$500 at a shop.

What causes P2251 most often?

A failed air-fuel sensor or an open circuit in the wiring.

🔗 Related Codes

P2237P2243P2252P2253P0131