96 nissan altima


#1

about two weeks ago i was having trouble with the check engine light on my 96 nissan altima. The code showed there was a problem with the knock sensor. It was not a problem I addressed immediately and in the mean time my check engine code also showed there was a problem with the egr solenoid valve. I replaced the knock sensor and cleared the check engine light but it is still throwing a code for the egr solenoid. I have checked the solenoid and it seems to be working properly. I have used a vacuum pump to check various hoses and all are in working order. I removed the egr valve and cleaned up the carbon deposits. everything seems to be working fine. the egr valve is not clogged or sticking. The only thing that seems odd is that when the engine is cool the egr solenoid/evap purge solenoid valve is getting a 12 volt signal however when the engine is hot it reads the same…12 volts. This doesn’t seem right. Any suggestions? I’ve checked about everything and everything seems to be running normally. HELP! This is preventing my car from passing inspection.


#2

The DTC (Diagnostic Trouble Code) NEVER says that a part is bad. It says that expected voltages in particular circuits aren’t what they should be.
The “EGR/Canister Control Solenoid Valve” circuit always has 12 volts when the ignition key is in RUN or START. The EGR/CAN. is grounded (energized) whenever the ECM (engine computer) decides to. It “decides to” after it looks at the voltage signals from certain sensors (among them the tps (throttle position sensor) and others. You need the Nissan Service Manual (or, www.alldata.com) to find out which sensors to test.