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P0453 Fault in 1999 Mercury Cougar: Diagnosing Fuel Tank Pressure Sensor Issues

Model: Mercury 1999 Cougar Fault Code: P0453 Posted: 2012-10-03 12:10

My 1999 Mercury Cougar is displaying Diagnostic Trouble Code P0453. I have already replaced both the Pressure Feedback Sensor and the Vacuum Regulator Sensor, but the code persists. To isolate the issue, I disconnected each sensor one by one (excluding the fuel tank pressure sensor) and observed whether a new fault code appeared. Each time, a second code was generated upon disconnection, which suggests that the sensors are functioning correctly. After clearing the codes each time, P045-3 reappears immediately. This has led me to suspect the vapor canister may be faulty. Does anyone else see this as a likely cause or have alternative insights? Any experience with this code on a 1999 Mercury Cougar with a 2.5L V6 engine would be greatly appreciated.

Related fault codes
P0453
Comments (4)
Anonymous 2012-10-03 13:54

I'll double-check, but P0453 typically indicates either a high or low voltage reading on the sensor circuit. Do you have an OBD2 scanner? Check the freeze frame data—what was the voltage at the time of fault occurrence? Is your vehicle stock? Have there been any recent repairs? Specifically, is it a 2.0L or 2.5L engine?

Anonymous 2012-10-03 16:36

Yes, I have an OBD2 scanner, but I'm not familiar with 'freeze frame' data. My Mercury Cougar is stock and equipped with a 2.5L V6 engine. The transmission was replaced about two months ago. Thanks for the clarification.

Anonymous 2012-10-03 16:58

OBD2 scanners offer much more than just code reading—consult your scanner’s user manual or official website for detailed guidance. Simplified explanation: The fuel tank pressure (FTP) sensor operates at a standard 5V system. A P0453 fault suggests the sensor circuit is reporting an abnormally high voltage. When the fault occurs, the vehicle's ECU captures key conditions in the freeze frame data. Since each sensor has a unique address, you can use your scanner to view live sensor readings. Knowing the actual voltage being reported by the sensor helps pinpoint the issue. For example: If the reading shows 12V, it may indicate a circuit shorted to power—commonly found in fuel pump connectors. If the voltage is around 4.9V (which is unusually high), the fault is more likely due to a defective sensor or loose connection, as such readings are highly unlikely under normal conditions.

Anonymous 2012-10-08 11:37

Thanks for the helpful guidance, Kev2! Your explanation helped me identify and resolve the issue. The root cause was a dirty and loose electrical connection at the fuel pressure sensor. I accessed it by removing the rear seat—a relatively simple step—since there's a circular access panel under the seat that leads to the top of the fuel tank where the lines and wiring are located. I sprayed the connections with electrical contact cleaner and secured them firmly. After restarting the vehicle, the P0453 code disappeared completely. Problem solved! Thanks again for your support.