Control Pressure (Warm-Up) Regulator question

Ameer Antar antar at
Tue Sep 21 22:26:26 EDT 2004

As Huw mentioned the connector on the WUR isn't for a sensor, but a heating element, so the reading doesn't depend on temp really. Although your reading is a bit low, that seems to be normal for an older regulator (I've tested 3, all at about 12 ohms). That's really not an issue as long as it heats up, and even if the element is broken it will only cause issues during warm-up period of the motor.

The major issue is whether the WUR is regulating the control pressure correctly, which you can only test w/ a fuel pressure test kit. If you have other sensors or vacuum hoses to check, do that first, then if you still have problems look into getting a kit somehow. Check out SJM for a checklist of things to check. good luck.


   ----Original Message----
   Date: Tue, 21 Sep 2004 19:15:12 -0400
   From: Larry C Leung <l.leung at>
   Subject: Control Pressure (Warm-Up) Regulator question
   To: quattro at
   Message-ID: <20040921.192458.888.1.l.leung at>
   Content-Type: text/plain; charset=us-ascii
   Trying to assess whether or not my Warm Up Regulator is electrically 
   out of spec or not, or do I have to do the fuel system pressure checks:
   Patient, '89 200Q, MC2
   Bentley says that the temp sensor check value is "approximately 14 - 22
   Checking temperature range 68 to 86 degrees F (20 - 30 C), although I
   really think that this applies directly to the resistance measurement
   range, it's 
   part of the output test section of testing the unit. 
   At 75 degrees F (22.5 C), the unit resistance checks at 12.3 ohms. If I
   go for a 
   percentile basis, it's about 12 % below spec. Is the Bentley
   tolerance to this degree, or is the unit electrically okay?
   As always, TIA,
   LL - NY

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