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3100 Engine speed (RPM) sensor, signal missing

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Asherloperly
Posts: 2
Joined: 14 May 2024
Year and Model: 2004 C70
Location: United Kingdom

3100 Engine speed (RPM) sensor, signal missing

Post by Asherloperly »

This is driving me crazy!

C70 - MK1 - 2.0 - 2004

I removed the spark plugs and the fuel pump fuse to conduct a compression test on the engine, Although the compression was lower than I would have liked... between 130 and 140 across the 5 cylinders still high enough to have some life left in the engine.

I have now replaced the fuse and the plugs and......no start!

Checked for fuel, rail has good pressure of fuel and I can smell it! The engine cranks but seems to have no "Spark" plugged in the iCarsoft error reader and I get a 3100 error code. Engine speed (RPM) sensor, Signal missing. I made the mistake of changing the Crank Sensor and the (RPM) speed sensor on top of the transmission. Rookie mistake, check before changing parts!

Now I have the same issue, and the same error! The crank sensor has two pins and both have 12V at the plug so I guess no break in the wire.

Could this be the Cam sensor??? or actual teeth missing!?

What do you think? :?: :?: :?:

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xanthefin
Posts: 445
Joined: 4 May 2019
Year and Model: 1997 850
Location: Pluto
Has thanked: 106 times
Been thanked: 130 times

Post by xanthefin »

Or you put it not exactly correctly there where it wont reach to read teeths.

Footnote: I am not familiar with 2004 crank sensor at all i just saying my wild guess what can happen when changing it.

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