maf sensor

I know theis is a toyota forum, but I need your opnion on my wife's 01 Nissan pathfinder.

I just replaced the upstream O2 sensor on my wife's 01 pathfinder. after a week of driving, the SES light came on again with the same code. P0171. I reset it and the light came on again and I brought it to the mechanic.

They said it's the MAF sensor. and the code was P0170. is it possible for the MAF sensor to trigger a P0171 and a P0170?

and if the MAF sensor is really bad, what are the long term effects if I don't replace it?

thanks.

Reply to
Raymond
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It sounds like you have an OBD II code scanner. When you scan codes, always scroll the display down to check for multiple codes before clearing the codes. Codes will be listed from lowest number to highest number.

If the P0170 code was in there before, it should have shown up before the P0171 code. By the way, P0170 means that there is a fuel trim malfunction for bank 1. P0171 means that the system is too lean for bank 1

DTC's related to the Mass Air Flow sensor are codes P0100 through P0104.

Yes, although I'd suspect the O2 sensor before a MAF sensor, especially if there is not MAF trouble code. What kind of O2 sensor did you install? Is it OEM or aftermarket? Have you considered the possibility that the replacement O2 sensor is bad or incorrect? Have you checked the wiring and plugs for the O2 sensor?

If a MAF sensor is bad, it could set a trouble code or make the system run so lean or rich that the O2 sensor cannot compensate for it in closed loop operation.

Reply to
Ray O

ah, I forgot to mention, that the shop said that there was a P0100. I didn't check it the 2nd time the light came back on. I assumed it was the same code.

The shop replaced it so I'll have to double check with them the next time I get the check engine light.

Reply to
Raymond

Keep this in your 'toolbox' :

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It indicates p0100 is a 'generic' MAF code. Are there any others, other than the p0170 and 171?

Reply to
Hachiroku

the first time it was P0171 & P0174. both upstream oxygen sensors were replaced.

I'll have to wait aga>

Reply to
Raymond

if the MAF sensor is bad, will I notice it with how the engine runs?

can the MAF sensor be partially working like the O2 sensors? or is it always either good or bad?

Reply to
Raymond

First of all, don't assume that the trouble code is the same if the check engine light comes on again.

Maybe but I doubt it unless the MAF sensor is in really bad shape.

MAF sensor operation can be marginal, not bad enough to set a code that the MAF sensor is inoperative but still not giving good info to the ECU.

All this is speculation until you get another check engine light.

Reply to
Ray O

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