240 1990 Check Engine-High fuel consumpt. with 2 ECU codes

1990240Volvo · Post by **1990240Volvo** » 08 Jul 2009, 15:22

My 1990 Volvo 240 Sedan has approx. 240k miles on it. For a while now it has been consuming fuel at a high rate. The ECU had fault code readout 232 (faulty fuel injectors) and 113 (fuel system compensating for rich air/fuel mix). It also puffs out small amounts of black exhaust. A trusted and reliable mechanic told me it was the ECU, so I got one used (from a wrecked 1991 240 w/120k miles) and installed it. After a few miles the CHECK ENGINE light came on again and it puts out the same exact codes. The mechanic seems to think I have the ECU I installed is faulty-which seems ridiculous since it reads out the same codes as the last. Does anyone have any ideas?

mtux960 · Post by **mtux960** » 09 Jul 2009, 13:28

I would have to say your mechanic is off on his judgement.. unless you happened to find another broken one that errors the same code.. So I would think the codes are correct.. at least that what my mind would think... I'm not really mechanically-inclined so much.. but reading online.. that error code might be caused by a faulty Oxygen Sensor..

1990240Volvo · Post by **1990240Volvo** » 11 Jul 2009, 14:22

That's exactly what I thought. And I do think that the oxygen sensor might be causing (at least some) of the problem. I tried out some troubleshooting (as outlined in the Bentley manual-taking meter readings at the connector for the ECU. The pin connecting from oxygen sensor to ground did not produce continuity-like it should according to the manual. I am just a bit perplexed as to why the fault codes would not read out any code pertaining to the oxygen sensor. Also, when clearing codes it takes about 5 min. for the check engine light to appear, could this be because it is taking the oxygen sensor heater (as my model has) time to heat up? I am a bit trouble at what to do as I have been thinking about taking it to an official Volvo dealership (the one nearest where I am charges $85/hr!). I figured the problem would be found but I am a bit shaky on how much time it could take. Any idea or recommendations?