I love my Check Engine light.

[SilverSHO]

I was coming back from town about half an hour ago, and about a half mile from school the light flashed on and damn near gave me a heart attack. It stayed on for about twenty seconds, then turned off. Needless to say, I pulled codes as soon as I got back.

Immediate KOEO codes were clear. Stored codes were 41--rear O2 sensor reading lean; 49--SPOUT circuit open/defaulted to 10 deg. BTDC; and 95--fuel pump secondary circuit failure. Some of the KOER codes, I think, are just because I botched the test. It gave me 73--insufficient TP output change; 25--knock sensor not detected during dynamic response test; 74--BOO circuit failure during dynamic response test; and 41 again.

So I know I need at least one O2 sensor, but all the other codes have me stumped. Any help would, of course, be greatly appreciated. thumbs_u

 

[sdpatt]

The only code that jumps out at me is the 41. You probably should replace both sensors if they have been installed longer than 60,000 miles. Since you have the two-digit codes you must have an MTX (pre-'92) and the best sensor for your car is the Bosch 13942 from AutoZone or AutoZone.com for $33.99+tax. You will probably notice sharper response and slightly better fuel mileage after replacing the O2 sensors.

I would clear the codes by re-running the test and pulling the jumper while the codes are being displayed. The 49 code is somewhat troubling, but if your engine is operating with normal power output, the SPOUT circuit must be intact. If the engine was defaulted to 10 degress BTDC, you would definitely know about it. There would be a great loss of power. You can generate this code by unplugging the SPOUT plug or one of several sensor inputs to the DIS or the rear connector on the DIS. Had you done that?

 

[SilverSHO]

I've been getting the 49 in CM for quite a while now, but I'm thinking that it might not show up if I clear the codes. The DIS was replaced June 2001, so I'm wondering if that might have anything to do with it. I don't recall ever seeing the 49 before that. Right after I got the car, though, I did notice a sudden, significant loss in power one night, and the new DIS seemed to cure that, so I think the original DIS could have been the problem.

I'm pretty sure I could use new O2s too; the ones in the car right now only have a couple thousand miles on them, but they were on when I couldn't figure out what was making the Y-pipe glowing orange long ago (not a problem anymore), so I'm thinking the excessive temperatures might have fried one or both of them. My guess is that at least part of my horrendous gas mileage is because EEC is getting a lean reading from that back sensor and constantly overcompensating on the rich side.

Oh...which cylinder bank is the rear one, the 123 side or the 456?

 

[sdpatt]

If the codes had not been cleared since the DIS module problem, that could have been the source of the 49 in the memory codes. The rear (rear of the car) bank is the one by the firewall, cylinders 1-2-3, also known as the right bank. The front bank by the radiator, cylinders 4-5-6, is also known as the left bank.

Scott