Service Engine Soon

jbl99 · #1 (**permalink**) 07-03-08, 03:50 PM

Hello, I have a '94 SLS, 4.6L. Service Engine Soon light came on today and it started running rough. I checked the codes and they were, PCM 34,43,45,71. I have a book on what they mean. Do I need to replace the map sensor, and the two front 02 sensors? Thanks

Necrosan · #2 (**permalink**) 07-03-08, 04:32 PM

I don't recognize any of those codes, but if that's what they came back as in y'r book, I'd assume you need to change what it recommends.

**Ranger** · #3 (**permalink**) 07-03-08, 10:39 PM

I think based on those codes, I'd start with the MAP sensor.

carnut · #4 (**permalink**) 07-04-08, 03:37 PM

Codes NEVER tell you what to replace! They tell you what circuit to diagnose. For instance you will get a MAP code if the wiring or vacuum hose to it are faulty, so replacing the MAP was a waste of money and time. You need the diagnostic trees in the factory manual and test equipment to properly diagnose why.

notalinkinguynemore · #5 (**permalink**) 07-04-08, 04:31 PM

change your map sensor. I have a 94 and the same thing happened to me. its real easy too. im not sure about the o2 sensors but if you got the cash it aint gonna hurt to change it.

carnut · #6 (**permalink**) 07-04-08, 05:43 PM

This car's diagnostic capability along with the service manual will keep you from throwing parts (MONEY) at it. Do it right the first time. My 84 and my 91 still have their original MAP sensors. The manual says that wiring integrity and hose connections are the things to check first as part of diagnosis. How many miles on this car?

jbl99 · #7 (**permalink**) 07-05-08, 03:14 PM

The car has 84000 miles. The map sensor and the front o2 sensor and egr valve were changed about a year and a half ago. It ran fine untill now.