Repair 7

What Is the Trouble Code PO452 on a 2001 Chevrolet Silverado

The 2001 Chevy Silverado 1500 came with either a 4.3-liter six-cylinder, 4.8-liter eight-cylinder or a 5.3-liter eight-cylinder engine. The six cylinder base model was offered with a five-speed manual transmission, but the extended cab and other models equipped with an eight-cylinder only included a four-speed automatic transmission; with or without four-wheel drive. Despite the many differences and options available all of them have a fuel tank pressure sensor that is used to detect the amount of pressure or lack there of. Code P0452 is directly related to this sensor, but the reason your Silverado is displaying this trouble code can vary and will require some inspection.

Fuel Pressure Sensor Operation

The fuel pressure sensor is connected to the powertrain control module or PCM via a five volt reference signal and a ground. The sensor relays a voltage back to the PCM in relation to the amount of pressure inside the gas tank and is used to detect leaks in the evaporative emissions system. A high voltage return signal indicates tank pressure is low and a lower voltage return signal indicates a higher tank pressure.

The Trouble Code

Code P0452 is set anytime the ignition is on and the return voltage signal is less than .1-volts for longer than five seconds. The code will not be set until the PCM test fails twice consecutively when the ignition is cycled. In general code P0452 indicates an evaporative system leak somewhere in the system or a failure with the fuel pressure sensor. Double check your diagnostic trouble codes before attempting diagnoses because if P1639 was also set with P0452 there is a short to ground in the 5-volt reference circuit inside the PCM, requiring the PCM be replaced.

Checking The Fuel Pressure Sensor

The fuel pressure sensor on your Silverado is connected to the fuel pump module and is located inside the tank; however, the harness connector extends upward and is outside of the fuel tank. There are three wires connecting the PCM to the sensor; grey is for the five volt reference signal, black is the pcm connected ground and dark green is for the signal sent back to the PCM. First and foremost check the wiring harness from the sensor connector to the PCM for any damage and fix as necessary. Disconnect the pressure sensor harness and set your digital multimeter to the volts setting. Turn the ignition key to the on position and probe the gray wire and black wire, you should receive five volts in this case the PCM is sending the proper signal and is not at fault. Connect the harness to the sensor and probe the dark green wire with the positive multimeter probe and direct the negative to a known good ground. ; if there is no reference signal the sensor is faulty and needs to be replaced. If the signal is between .1 and 5 volts examine the harness up to the PCM for a break in the circuit.

Replacing the Sensor

Replacing the sensor will require draining the fuel tank and lowering the tank from the vehicle. As always remember to relieve fuel system pressure by depressing the schrader valve on the fuel rail with a screwdriver wrapped in a shop towel. Disconnect all fuel tank lines, connectors and vacuum lines, then remove the tank from under the vehicle. Remove the fuel pump lock ring and remove the module. Remove the screw for the sensor, it is located just above the electrical pump. Install the new sensor and set the harness into place. Lower the module into the tank and replace the lock ring gasket. Tighten the fuel tank straps to 30 foot-pounds alternating back and forth. Use a scan tool to clear any trouble codes before driving the vehicle.