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Re: Engine code 512 900 1995

posted by  someone claiming to be Jerry Warren on  Sat Nov 3 16:31 CST 2001 [RELATED]

Based on the Volvo manual on fault tracing, the code has to do with short fuel trim. The ECM receives a signal from the O2 sensor on the air/fuel mixture. If the air/fuel mixture deviates from a ratio = to 1 the short term fuel trim compensates for it by adjusting the injection period. If the short term fuel trim remains lean for more than 3 minutes and the engine temperature is greater than 167F the 512 code is sent to the DTC.

Possible problems

Faulty sensor signal

High fuel pressure.

Sympton

High fuel consumption

Uneven running

Check the MAP sensor voltage should be around 2.3 to 2.4 with everything off and the engine warm at idle. Also check the MAP ground.

Another area to check is the 55 pin connector in the central relay unit(no. 13)for oxidation. Ignition off and MAP disconnected.





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New Engine code 512 [900][1995]
posted by  someone claiming to be John  on Sat Nov 3 13:43 CST 2001 >


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