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Code P0120 - Throttle Position Sensor

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

Dmck
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Year and Model: 1995 850
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Dmck

Code P0120 - Throttle Position Sensor

Post by Dmck » Tue Aug 07, 2018 8:11 am

Hi all,

So after battling my car back from the grave (blown head gasket from broken water pump propeller) all I have left as a check engine code is for the throttle body position sensor

I already went to junkyard and switched out the throttle position sensor with another one. It could be possible I used a bad one again...

Other than it being the sensor itself, what other issues could be causing this code to fire?

It would be great to not have the check engine lights glow burning a hole in my brain.



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erikv11
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Re: Code P0120 - Throttle Position Sensor

Post by erikv11 » Tue Aug 07, 2018 1:14 pm

How is the TPS connector on the wiring harness, and the little pigtail back to the main harness? Maybe a wire got pinched etc.

How about the fuel relay under the radiator cowl, is it connected well and its connector not falling apart? I have read of problems with this relay affecting the TPS, but I've never checked out the wiring diagram to try to understand why.


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

Dmck
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Joined: Fri Jun 29, 2018 1:41 am
Year and Model: 1995 850
Location: Austin, TX
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Dmck

Re: Code P0120 - Throttle Position Sensor

Post by Dmck » Tue Aug 07, 2018 1:29 pm

I'll look into it. I fooled around with the wire a tiny bit this morning and reseated it into the TPS

When I first start ignition the check engine light isn't on. It takes a second to click on.

If I start the engine and then rev it or take out of park, it turns on right at that moment of either of those actions.

If it were wiring I would think it would be an automatic check light and not delayed, but not sure.

I'm going to take off the intercooler tube tonight and fiddle



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misha
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Re: Code P0120 - Throttle Position Sensor

Post by misha » Tue Aug 07, 2018 3:17 pm

Dmck wrote:
Tue Aug 07, 2018 1:29 pm
...If it were wiring I would think it would be an automatic check light and not delayed, but not sure...
No...the ecu will need to go through about 3 check cycles before it sets check engine light ON.


'97 850 2.5 20v /fully equipped/ Motronic 4.4 / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

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