1991 240SX Engine Light On

[JCMITO]

I decided to wash the engine in my 240SX. Covered the distributer as instructed everywhere. The engine looks great. After a few days I began to loose power. I pulled over one day and looked under the car. The catalytic converted was glowing red. I managed to drive it home. It turned out that water had gotten into three of the 4 spark plugs. I did a tune up and replaced everything that needed to be replaced. The Catatyc Converter began to rattle probably due to all the gas it had to burn and raised the temperature and probably melted some of the metals in it. I bought a new one and had it replace since it had to be welded. New Cat and installation came out to about $180. I bought it in one place and had it installed in another place. The car now runs great, but the engine light came on. This happened about 10 yrs ago when I had to have the cat replaced in order to pass smog. I had it replaced and the light went out. Even though I suspected the old cat to be bad because of the rattling, the engine light never came on. I'm taking the car back to the shop that installed it to see if they can help me find the problem. Could the new cat be bad? Any idea how I can have it tested? The place where I bought it said that they can only test cars 96 and up. Mine is a 91. Any suggestions? Thanks guys

[OutToWinPAHC]

Could be a clogged/junked/burnt up o2 sensor, pull the code

[PyR0NiAk]

^ what he said.. There's a screw on the back of your ecu to test for codes..

[JCMITO]

I took it to the shop and they told me it's not the catalytic converter. They checked it out at no charge and told me that codes 11(crank sensor) 32 (EGR) and 34(Knock sensor.) They told me to have it diagnosed at a shop so that they can point at the right thing to replace. I took it to a shop and they charge me $145 to diagnose. I'm unable to do it now. The car runs fine but I know it will have to be smogged soon and I don't think they will attempt to test with the engine light on.

[OutToWinPAHC]

Hmm you got it wet and clogged the cat and top side. I can see the knock and EGR being bad because of that.

[AZ89two4Tsx]

I'm assuming you live in California because iirc the engine light is only for CA cars.

I would check all your vacuum lines. That can easily trigger that stupid light. When I washed my engine it blew off multiple vacuum lines causing my engine to run like s***. I had to limp it home on three cylinders. After reconnecting all the vacuum lines, bam, runs great.

Check behind the valve cover. There's a bunch of little hoses/lines that you might have blown off.