P1274

A/F Sensor 1 Rich Shift Monitoring (Bank 1)

Car Fault Codes Nissan Emissions & exhaust

Can you still drive? Yes, normally

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 2 hours

Typical cost SAR 150 to 1,500

What it means

This is a Nissan-specific code; the same number can mean something different on other makes. It means the signal from the front air/fuel ratio sensor (sensor 1, before the catalytic converter) on bank 1 is consistently shifted toward rich. The sensor may be aged, or the mixture may really be rich from excess fuel.

Models covered: Nissan models with air/fuel ratio sensors, mainly around 2003–2008.

Symptoms4

Check engine light on.
Higher fuel consumption.
Fuel smell or dark exhaust smoke in some cases.
Rough idle if the mixture is actually rich.

Possible causes6

An aged front air/fuel ratio sensor, or one contaminated by carbon or oil.
A leaking or over-fueling injector.
High fuel pressure from a faulty pressure regulator.
Wrong readings from the mass airflow (MAF) sensor, or a clogged air filter.
An EVAP purge valve stuck open, letting in extra fuel vapor.
A fault in the sensor heater or its wiring.

How to diagnose6

Read all codes; P0172 alongside this code points to a truly rich mixture.
Watch fuel trims; large negative values mean the computer is constantly pulling fuel.
Check the air filter and the MAF reading against the specification.
Measure fuel pressure and make sure the injectors do not leak after shutdown.
Check the EVAP purge valve to confirm it does not stay open.
Inspect the sensor for oil or coolant contamination, which can point to an internal engine problem.

How to fix6

Replace a clogged air filter and clean the MAF sensor.
Replace the EVAP purge valve if it is stuck open.
Clean the injectors or replace any leaking one.
Repair the fuel pressure regulator if pressure is high.
Replace the bank 1 front air/fuel ratio sensor if it is confirmed to have drifted.
Clear the codes and drive until the self-test completes, then confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when an air filter or sensor cleaning is the fix, and rises if a new sensor, injectors or a pressure regulator are needed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Can a rich mixture harm the catalytic converter?

Yes, if it is truly rich for a long time. Extra fuel overheats the catalytic converter and can clog or destroy it, so do not leave this code unrepaired.

Why check the sensor for oil?

Oil or coolant on the sensor contaminates it and skews its signal, and it can point to oil burning inside the engine that must be fixed or the new sensor will fail too.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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