P2256Fuel & Air Metering

O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1

P2256 means the negative current control circuit of the air-fuel ratio sensor on Bank 2 Sensor 1 is reading too low, usually from a short to ground or a failed sensor.

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

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

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

45%

The negative pump cell circuit fails low.

#2Short to ground in wiring$50-$300

30%

A damaged harness pulls the circuit low.

#3Connector corrosion$50-$200

15%

Poor contact affects the circuit.

#4ECM fault$300-$1000

10%

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 P2256

1Inspect wiring for shorts to ground

2Check the connector for corrosion

3Test the negative control circuit

4Replace the air-fuel ratio sensor if confirmed

❓ Frequently Asked Questions

Can I drive with P2256?

Short-term yes, but repair it to restore fuel control.

How much to fix P2256?

Usually $200-$500 at a shop.

What causes P2256 most often?

A failed air-fuel sensor or a short to ground.

🔗 Related Codes

P2255P2257P2252P2247P0151