CEL is on

[Crystal Shine]

Hello,

My car is 2000 Boxster S with 58500 miles. CEL is on today (solid light, no flashing).

OBDII scanner read code P1275 and P0133.

50,000 miles ago, I had same codes. Cleared them and didn't do any repairing at that time.

Someone is suggesting to change MAF sensor instead. But the above code is pointing to 02 sensor @bank 1 sensor 1. What do you suggest to approach solving the problem? The car run okay now.

[Loren]

P0133 Aging of Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Below Lower Limit

P1275 Aging of Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Below Lower Limit

"The diagnosis of "oxygen sensor aging" helps to identify oxygen sensors that exceed emission limits because of aging.

During the diagnosis of oxygen sensor aging, the DME control module monitors the period of the sensor signal. With an old sensor, the duration of the period is too long, i.e. it is more difficult for the sensor to diffuse oxygen into the exhaust gas. Reasons for this could be frequent driving in the lower load range (city driving, short distances, etc.) or a contaminated sensor."

The OBD II manuals says "Replace the sensor"

[Crystal Shine]

P0133 Aging of Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Below Lower Limit

P1275 Aging of Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Below Lower Limit

"The diagnosis of "oxygen sensor aging" helps to identify oxygen sensors that exceed emission limits because of aging.

During the diagnosis of oxygen sensor aging, the DME control module monitors the period of the sensor signal. With an old sensor, the duration of the period is too long, i.e. it is more difficult for the sensor to diffuse oxygen into the exhaust gas. Reasons for this could be frequent driving in the lower load range (city driving, short distances, etc.) or a contaminated sensor."

The OBD II manuals says "Replace the sensor"

Loren,

Which sensor do you suggest I should change? Where is it located? many thanks.

[Loren]

That would be the sensor closest to the engine (before the cat) on the right side (passenger side on US cars).