wb8yjf

Wifes 1997 Intrepid 3.5 acting weird. Started with having to bleed the radiator (fluctuating temp), got that going, now getting code 21 (oxygen sensor) and code 17 (knock sensor). Are these sensors easily located? I know this car is a real pain for getting to some things....any help is appreciated!

Thankx,
Jon

AWP9521

Code 21 in my book says "Problem with Oxygen Sensor signal circuit. sensor voltage not fluctuating. The code 17 in my book says "Engine is cold too long. Engine coolant temperature remains below normal operating temperatures during operation (Check the thermostat). Another member has posted a very good listing of code descriptions for 93-97 LH Vehicles and a link to codes for 98 and up OBD II vehicles, you can view the thread HERE.

The O2 sensor is on the exhaust manifolds, your car should be OBD II which means there are 4 of them to choose from, 2 on each bank. Your Knock sensors (2) are located underneath the intake Manifold in the Valley of the Engine Block. Like I said, your car should be OBD II since that was instituted beginning with the 96 model year, you might want to take it to a dealer or an AutoZone and get the proper OBD II Codes from it for proper diagnosis

wb8yjf

THANKS AWP! Wife is taking my Jimmy to work tomorrow, I'll go to Autozone to see what they read. I wuz using the ignition key method of getting codes. Are the sensors a b**ch to get at? (I sure hope not, MAN its COLD here lately! )

Thanks!

wb8yjf

BTW, just curious, will the knock sensors react to another problem..ie: the oxygen sensor being bad & causing the engine to react in a way to cause a false reading on the knock sensor? Just curious..I service electonics and see that kinda thing a lot.... THANKS!

theFREAKnasty82

The knock sensor is a piezocrystal microphone that detects engine ping (knock). What it does is when it detects ping, it retards engine timing. Theoretically, it shouldn't affect the reading of the oxygen sensor(s), but if the knock sensor is still sending a signal to the PCM that there's a significant amount of ping, the engine will continue to retard timing and that could lead into a lean and/or rich fuel mixture, thus your O2 sensor(s) will pick that up and that could give your the codes that you're having now.

wb8yjf

That makes sense. How hard are these knock sensors to get at on this cramped engine?

AWP9521

The cooling system has to be drained, the Intake ducting has to be removed, the Intake Plenum has to be removed, the Fuel Injector Rails have to be removed, and finally the Intake Manifold has to be removed just to gain access to the Knock Sensors.

Quite frankly I don't follow why your are leaning towards the Knock Sensors unless the OBD II diagnostics are stating such, the "Code 17" you asked about is saying that your engine is not warming up fully or taking too long to warm up which suggests that the Engine Thermostat is stuck in the open position or missing entirely. The engine must get to at least 160 degrees for everything to start operating correctly, and if it's runs too cold for too long it throws everything out of whack. None of the codes in my book refer to the Knock Sensors.

wb8yjf

I got the heating problem fixed prior to this happening, that was air in the system & I put in a new thermostat. Then these codes popped up a couple of days later. I got the disc. of these codes from a Haynes techbook on codes. I still want to take it to autozone asap and have them do a more thorogh read of the cpu though. Believe me, if I can avoid all that work, I will!