P1148Fuel & Air Metering

Closed Loop Control Function (Nissan/Infiniti, Bank 1)

P1148 is a Nissan/Infiniti code meaning closed loop fuel control on Bank 1 is not functioning, usually because the air/fuel ratio sensor is not responding correctly so the PCM cannot maintain closed loop.

🚗 Yes, short-term, but expect worse fuel economy and emissions.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Failing air/fuel ratio sensor Bank 1$100-$350

45%

A slow or dead A/F sensor prevents closed loop.

#2Exhaust leak near the sensor$50-$400

30%

Leaked air skews the sensor and blocks closed loop.

#3Wiring or fuel trim issue$50-$400

25%

Wiring faults or a severe lean/rich condition prevent closed loop.

🩺 Common Symptoms

Check engine light
Reduced fuel economy
Rough running
Failed emissions test

💰 Repair Cost: DIY vs Shop

DIY Cost

$50-$350

Shop Cost

$150-$500

📋 Free OBD2 Code Cheat Sheet

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🔧 How to Diagnose P1148

1Inspect the A/F sensor wiring and connector

2Check for exhaust leaks near the sensor

3Review fuel trims for a lean or rich bias

4Replace the A/F ratio sensor if it does not respond

❓ Frequently Asked Questions

Can I drive with P1148?

Short-term yes, but the engine runs in open loop with worse economy and emissions. Diagnose soon.

Is P1148 a Nissan code?

Yes, P1148 is a Nissan/Infiniti closed loop control function code for Bank 1.

What fixes P1148?

Replacing the Bank 1 air/fuel ratio sensor usually resolves it after ruling out exhaust leaks and wiring.

🔗 Related Codes

P1168P0133P0134