CEL Code P1031

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Jul 30, 2005 | 09:01 AM

revhi

Thread Starter

Joined: Jan 2003

Posts: 8,831

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From: Used Jersey

CEL Code P1031

P0131 Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Circuit Low.

This MIL is on in my girlfriends 99 Si. Ive searched around and it seems that no one has had this code pop up in either the Civic or S2000 community. Is it just a bad sensor? The car is completley stock and has about 40k. .

Jul 30, 2005 | 01:09 PM

Wisconsin S2k

Registered User

Joined: Sep 2001

Posts: 9,792

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From: Milwaukee Area

first try resetting the ECU.

it could be the HO2S sensor is bad. could also be a connection between the sensor and the ECU.

Jul 30, 2005 | 01:53 PM

Slows2k

Former Moderator

Joined: Sep 2002

Posts: 45,365

Likes: 428

From: Mother F'in TN

Usually it's a bad sensor, with a biased low output voltage. You have to monitor the 02 output voltage with the engine running to verify the sensor is bad.

If the sensor input volts stay below .5 and don't rapidly change from 0-1V, the sensor is bad.

Off to Car talk as well, cuz it's for a Civic