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Help understanding diagnostic codes on 92 740T Auto Wagon

Help, Advice, Owners' Discussion and DIY Tutorials on all Volvo's "mid era" rear wheel drive Volvos.

1975 - 1993 240
1983 - 1992 740
1982 - 1991 760
1986 - 1991 780
1990 - 1998 940
1990 - 1998 960
1997 - 1998 V90/S90

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AScott
Posts: 2
Joined: 23 April 2007
Year and Model:
Location: Birmingham, Alabama

Help understanding diagnostic codes on 92 740T Auto Wagon

Post by AScott »

Hi, I'm wondering is I could get a little advice on the diagnostic codes I just pulled.

I've only had this car a few months, and I'm trying to get things working right again.

I know my turbo hose, and the one going into the intake are both damaged, and may be the entire cause of my problems.

I had 2 codes stored. 2-3-1, and 1-1-3. Both refer to the "fuel trim (lambda control)".

The first one says the causes of the fault are "air leaks, low fuel pressure, bad sensor".

The second says the causes of the fault are "mixture incorrect, O2S wiring fault".

Could someone give me some insight on what I need to be looking at. I'm not a stellar mechanic, but have always worked on my own cars. I still don't have a shop manual for this car.

My biggest problem is really, really, bad fuel consumption. Both codes said that was a symptom, too.

Thanks in advance,

Al

wojeepster
Posts: 259
Joined: 15 November 2005
Year and Model:
Location: Hendersonville, NC

Post by wojeepster »

o2 sensor controls fuel injection closed loop, when they get old they tend to go rich. You can measure signal wire with digital volt ohm meter (not analog, needle) You should get .1-.9v and it will change regularly. If it is stuck then you either have a lazy o2 sensor or some other problem that is making it go rich. Check air filter, check fuel pressure for if it goes high (regulator stuck) it can go very rich.

AScott
Posts: 2
Joined: 23 April 2007
Year and Model:
Location: Birmingham, Alabama

Post by AScott »

That's about what I gathered after reading a little more. Thanks for the reply.

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