got a 94 850,,just got her,,,,A fine looker,,,problem with stalling after semi warm,,will start right back ,,with one incident of hard starting back,,,first code reading was MAF and O2 ,,,cleared codes and run again,,,MAF code come up,,(121),,MAF connector terminal #2 indicated resistance,,.....figure the O2 code was from other malfunction,,,,Do I look toward the brain box or the MAF...how do you test a MAF sensor?....recent purchase from private stock,,,well maintained and serviced regularly by dealer,,,My research shows a special plug and adapter is needed to test the fuel ECM,,,if I needed one where do I look for it?.......Hoping this Is an easy fix but also know electrical and electronics can be a roll ya eyes ,grit ya teeth,sob ,,bit the the bullet....any input????THANX 4 any ..........AL

 

Welcome to the forum.

Most likely the MAF sensor has gone south. See attachment for testing procedure. If it is turbo it should have the OBD-II port in front of the shifter right under the coin holder. Also see: http://volvospeed.com/Repair/maf_secure.php


JPN

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Check the tightness of the MAF Connector. If that doesn't eliminate the problem, I would suspect the MAF itself is bad

 

A bad MAF could also throw O2 sensor codes.