Oldsmobile Aurora P0404, P0300 And P1645

Question:
Problem with my 1997 Oldsmobile Aurora 4.0.The service engine soon light is on. Sometimes it turns off but only for about 5 miles and then comes on again. I used a computer reader and I found 4 codes :P0404 P0300 P1645 and P0404 again. I put an injector cleaner in my fuel and now I'm thinking to replace the EGR valve. Do you think that is going to solve my problem or what else should I do?I'm also running out of time because in about 2 weeks I have to do the emission test on my car.I would really appreciate your advice. Thank you.

Answer:
OK, lets go one at a time. First check ALL fuses underhood and in the fuse block under the rear seat. P0300 misfire. Need to find out which cylinder. You need to see live data for that. A code reader cannot do that. 4.0l v8 are well know for corroded ignition coil towers. Just pull plug wires off coils one at a time and look for corrosion on coil and wire.

Also could be a burned plug wire at the spark plug. The ones in the back are usually the culprit. P0404 is EGR pintle open position error. The pcm(computer) is not seeing the correct feedback position. Either egr is bad, or just full of carbon. Could try to remove valve, tap on the ground to clean out any carbon. Or use compressed air. Since it came up twice, sounds like it is current and history code.

P1645 is the evap system purge control valve circuit. Possible bad solenoid, or connection problem. If you can use a volt/ohm meter, check for 12 volts at pink wire to make sure you have correct voltage in.

The problem is; how long have these or some been there, or did they all come at the same time. If happened after radiator replacement, then would suspect a harness got moved or pulled causing a loose connection. Aside from all these things, some normal places of poor connection/broken wires is the harness going into the firewall below and toward the pass. side of the master cylinder.

Clear all codes and grab and move that and other harness to see if that causes the light to come on. The egr wires, evap. Solenoid wires, and injector wires all go in that harness and travel under the throttle body. It is possible that these are all or some related. That was a common problem area.

If you are familiar with auto repair, could do some of these things yourself, if not, would suggest a good repair facility, since there are several things, different systems having problems. Over the years have had any one of these parts go bad (egr valve, purge solenoid, coils, wires, plugs, injectors)Let me know if i can be of more assistance.

Getting ready to buy one at a good price, all looks good just the check engine light is on. I was told the converter and 4 o2 were changed. I can clean the EGR first to check for build up but I have a feeling the MAF can cause the same problem?
 No way for me to give you any help without knowing the code numbers stored in the computer. Get them scanned and let us know.