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P0133

O2 Sensor Slow Response Bank 1 Sensor 1

The engine computer is seeing the front oxygen sensor on bank 1 respond too slowly. This can be caused by a bad sensor, exhaust leaks, wiring problems, or engine running issues. It can hurt fuel economy and emissions.

Severity3/5 Moderate
Can I drive?⚠ With caution

You may usually drive short distances, but the vehicle may run richer than normal and use more fuel. Fix it soon, because long-term driving with this fault can damage the catalytic converter if the engine is also running poorly.

DIY
$20–$200
Shop
$150–$500
Difficulty
intermediate

What It Means

P0133 means the ECM detected delayed switching from the upstream air-fuel or oxygen sensor on Bank 1, Sensor 1. The sensor is not changing voltage or current fast enough during normal operation, so the ECM cannot accurately correct fuel mixture. The fault may be in the sensor itself, the wiring, the exhaust system, or an engine condition that affects sensor response.

Symptoms

Common Causes

1. Aging or contaminated upstream oxygen sensor on Bank 1high
2. Exhaust leak near the sensor or manifoldhigh
3. Damaged, corroded, or loose sensor wiring or connectorhigh
4. Engine running too rich or too lean from another problemmedium
5. Mass airflow sensor, vacuum leak, or fuel delivery issue affecting mixture changesmedium
6. Faulty ECM or rare calibration issuelow

Related Codes

FAQ

Is P0133 usually a bad oxygen sensor?

Often yes, but wiring problems and exhaust leaks are also common. The sensor should be tested before replacing it.

Can a dirty air filter cause P0133?

A dirty air filter usually does not cause P0133 by itself, but engine mixture problems from intake or fuel issues can contribute.

Will clearing the code fix the problem?

No. The code will return if the slow sensor response or the underlying engine problem is still present.

Can I pass emissions with P0133?

Usually not if the check engine light is on or the monitors are not ready.