I get this SES light on almost evertime I punch the gas. I had autotap on the car and it read P1639 code.. 5 Volt reference code..bluh bluh.. Anyone have any clue of where to look first..

 

Could it be your TPS showing over 5 volts?

you play with your TB any?

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DaveD
1998 WS6 #207
-ARE Stage II Head/Cam
1998 Regal GS
-It Has Boost

The Phantom of CamaroZ28.com
Http://PhantomTA.cz28.com

 

Circuit Description: The PCM uses a common 5.0 Volt Reference circuit as a sensor feed to the Fuel Tank Pressure sensor and the A/C Refrigerant Pressure sensor.

The PCM monitors the voltage on the 5.0 Volt Reference circuit. This DTC sets if the voltage is out of range.

Fuel Tank Pressure Sensor:

The Fuel Tank Pressure sensor is a sensor much like the MAP sensor. The Fuel Tank Pressure sensor measures the difference between the outside air pressure and the air pressure (or vacuum) in the fuel tank.

The Fuel Tank Pressure sensor mounts to the fuel tank sending unit. A three wire electrical harness connects the sensor to the PCM. The PCM supplies a 5.0 volt reference voltage and a ground to the sensor. The sensor will return a voltage between 0.1 and 4.9 volts on the signal circuit.

Hope this helps - I had a bad fuel pump already, at 25,000 miles. Don't know specifically if it was the same DTC (diagnostic trouble code). My SES light was coming on intermittently. Since it's sensing pressure (or vacuum), it might be the gas cap?