2G P1105 code problem

[turbo510]

So the CEL came up on my 99 gst and the p1105 code (fuel pressure solenoid) came up. I cleaned up the connection plug and reset it by taking off the battery terminal. Drove around a little bit and it stayed off for a few days but came back on. I thought that maybe the solenoid itself was bad so I tested it by unplugging it and directly run wires from the battery and checked the hose that goes to the fuel pressure regulator for suction and it works.

So then I thought the front o2 sensor might be the problem. I replaced that and the cel came right back on.

Is there anything else that can cause that code to pop up?
Any suggestions are appreciated.
Thanx.

 

[gofer]

Wierd. Seems like I've answered this once before? ---> 98 gst code p1105 Manifacture controlled fuel and air metering


Heres how you'd check the FPS to ensure that its operating correctly.

DTC P1105 - FUEL PRESSURE SOLENOID MALFUNCTION
NOTE: For terminal identification, see TERMINAL IDENTIFICATION in SELF-DIAGNOSTICS section. For circuit and wire color identification, see WIRING DIAGRAMS - 2.0L - TURBO article.


Disconnect Black vacuum hose from fuel pressure solenoid nipple. Disconnect electrical connector. Connect hand vacuum pump to solenoid nipple where hose was connected. Apply vacuum to solenoid. Go to next step.
Apply battery voltage across solenoid terminals. Vacuum should be maintained with voltage applied and should leak with voltage not applied. If vacuum is not as specified, replace solenoid. If vacuum is as specified, go to next step.
Turn ignition off. Check resistance between solenoid terminals. If resistance is 36-44 k/ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace solenoid.
Turn ignition on. Check voltage between ground and solenoid connector terminal No. 1. If battery voltage exists, go to next step. If battery voltage does not exist, check wiring harness between MFI relay and solenoid.
Turn ignition off. Disconnect PCM connector. Turn ignition on. Check voltage between ground and PCM connector terminal No. 3. If battery voltage exists, check PCM connector. If PCM connector is okay, replace PCM. If battery voltage does not exist, check solenoid connector. If connector is okay, check wiring harness between PCM and solenoid.​

It seems you missed a few steps in the troubleshooting process.