1998 Volkswagen Passat erratic temp guage

SFRYE

MEMBER
1998 VOLKSWAGEN PASSAT
4 CYL
2WD
AUTOMATIC
134,000 MILES

98 VW Passat w/ 1.8T engine. The temp guage often reads exceptionally low (cold) even after driving for more than a hour (mostly at freway speed). Sometimes temp will go up to middle of guage (190') then later on it might go back down. I know the engine should be (and could be) at normal 190' reading after driving for such an extended time period. What makes for the inconsistent reading? Maybe engine coolant temp sensor or maybe thermostat? Thanks for your help with diagnose and yes, I am more than happy to donate. Steve.

Sunday, October 25th, 2009 AT 7:05 PM

2 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,
Thank you for the donation,

This may be a faulty thermostat or a sender problem, when the temp goes from high to low is the heater still hot? If it is I would be considering a faulty sender, but if it was my car, I would be doing the sender and changing the thermostat and flushing the coolant if that has not been done for some time, if this problem persists after doing this re post for more assistance.

Mark (mhpautos)

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Sunday, October 25th, 2009 AT 7:11 PM

RASMATAZ

MECHANIC
75,992 POSTS

Hi sfrye and TY for the donation

Could be both one controls the engine temperature and the other reads it-check and test both and report back your findings

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Sunday, October 25th, 2009 AT 7:14 PM