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V70 turn over, CEL and camshaft sensor/reset valve issue

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Joined: Wed Jul 18, 2018 10:42 am
Year and Model: 1999 V70 2.4 T
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V70 turn over, CEL and camshaft sensor/reset valve issue

Post by Twopointfourturbo » Thu Aug 08, 2019 10:53 am

Hi everyone,

At first I thought this was a minor issue, but after additional headaches I thought I might ask here for some help. Short backstory, 99 V70 2.4T AWD, about 140000km/86000 miles. The check engine light/CEL started to come on sporadically a month ago, in combination with some starting issues (took about 8 seconds or longer to start, espcially at first starts in the morning). After my local garage looked at the ODB ECM readouts they determined it was a camshaft position sensor error - I decided to replace the sensor at another garage with experience on 850s and P1 C/S/V70s, this was 2 weeks ago.

After I get my moose back last week, the CEL is initally gone but the starter issues remain although different - either it starts normally on the first try (rare occurence), or it wont ever jump on at first, turning over endlessly but then starts normally on the second try. (common) At first I thought I'd wait a week or two and see if it gets better but now the CEL has reappeared, again very sporadically (a day or two at a time, with no regular interval periods) before disappearing again. I dont think the starter issues get better/worse if the CEL was on or not. After this I did another ODB readout at the second garage, getting the following codes: ECM-3000, ECM-644A, ECM-6440.

They're ECM codes concerning the same camshaft position sensor as before (ECM 3000 & 6440) as well as for the camshaft reset valve (ECM 644A) (According to the readout the codes are due to either a faulty signal or none at all, the readout didnt differentiate between both). I don't get how this could happen with a new sensor installed. The only idea I came up with so far would be to take a look at the cam reset valve and/or wiring of the position sensor and the ECM... your thoughts? Any ideas and suggestions are appreciated.