'98 Quest emissions problems---KS, EGR, TPS

Nov 19, 2008 2 Replies

My '98 Nissan Quest was up for inspection, and a borrowed scan tool showed 0325 (Knock Sensor) and 0400 (EGR Flow Error). After the usual drill where the local shop tried to convince me to pay $1000 to have the knock sensor replaced, I did some more digging and figured out that I needed to check the BPT vacuum line. It was, in fact, so degraded that part of it disintegrated in my fingers on contact. I replaced that and cleared the codes from the computer. I can't find out if that fixed the EGR problem, because....


--Issue 1: The Emissions Monitors will not reset. The state inspection shop can't finish the emissions inspection until they do, and my 15 days is up. We have driven it under all conceivable conditions for over 200 miles, and three monitors are still INC. This includes several dozen cycles of up to 45 mph, turn it off, repeat. The Nissan dealer service dept. said they typically had to drive them



3-4 days to reset them. It's been over two weeks. Anybody got any ideas?


---Issue 2: I looked through the "Review Data" feature on the scan tool. It appears to be reading the van's condition in real time pretty well. Pressing the accelerator ( in Park, in the driveway), causes the RPM reading to increase, but the "ABS TPS" reading remains at 0% when I move the pedal. Should I expect a change in the TPS reading under these conditions?


There is a specific sequence that has to be followed in a specific order to get through all the self tests and set the ready indicators. Your best bet is to try to find a downloadable copy of the factory service manual online. Its in there. The Nissan site will sell you a

24 hour license to download anthing you want, but I'm not sure if it goes that far back. Check first before giving them a charge number.

Don't worry about the knock sensor, it doesn't show up on the state inspection and it won't turn on the engine light by itself. If the EGR is not fixed, the engine light will come back on as soon as it sees the error condition on 2 consecutive drives.

Since the Quest also was sold by Ford as the Mercury Villager, you might give the local Ford garage a call for a second opinion.

Don't know. ABS units usually don't initialize until the car is moving at about 15 MPH.

I was hoping the Nissan service dept. was giving me the right drive cycle information, but it doesn't seem to work, so I guess I'll have to find the manuals.

Is this reading referring to the throttle position sensor?

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