Closed Loop Control (Bank 1)
What it means
This is a Nissan-specific code; the same number can mean something different on other makes. It means the engine computer could not enter closed loop control on bank 1, that is, adjusting the fuel mixture based on the front oxygen (O2) sensor signal, even though driving conditions allowed it. It usually appears together with front O2 sensor codes and is fixed by addressing those codes first.
Models covered: Nissan models, mainly around 1996–2003.
Symptoms4
- Check engine light on.
- Higher fuel consumption, because the computer runs on a fixed estimated mixture.
- Driving may feel normal with no obvious symptoms.
- Possibly a stronger exhaust smell or a failed emissions test.
Possible causes6
- A slow or failed bank 1 front oxygen sensor.
- A faulty O2 sensor heater that keeps the sensor from reaching operating temperature.
- A damaged wire or connector in the sensor circuit.
- An exhaust leak ahead of the sensor that lets in air and spoils its reading.
- The engine staying cold for too long because of a thermostat stuck open.
- A faulty engine computer (rare).
How to diagnose5
- Read all codes; if P0130, P0133, P0134 or P0135 are present, diagnose them first, as they are usually the root cause.
- Watch the front O2 sensor signal on a scan tool with the engine warm; it should switch quickly between lean and rich.
- Watch coolant temperature and confirm the engine reaches normal operating temperature.
- Check the exhaust ahead of the sensor for leaks or cracks.
- Check the sensor heater and wiring, and compare its resistance with the manufacturer specification.
How to fix5
- Repair the damaged wire or connector in the sensor circuit.
- Repair the exhaust leak ahead of the sensor.
- Replace the thermostat if the engine does not reach operating temperature.
- Replace the bank 1 front O2 sensor if its response is slow or its heater has failed.
- Clear the codes, then drive in varied conditions and confirm closed loop is reached and the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low when a connector or wire is the cause, and rises if a new O2 sensor, an exhaust leak repair or a thermostat is 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
Why does this code appear with O2 sensor codes?
Closed loop control relies on the front O2 sensor signal, so if the sensor or its heater fails, the computer cannot enter it. Fix the sensor codes first.
Will this code damage the engine?
Not directly, but running on an estimated mixture raises fuel use and can harm the catalytic converter if left for a long time.
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What was wrong? (optional)
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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