Last week I put in new ECM new O2 sensor and new plugs and the car has been running so perfect..... Today out of the blue the check engine light came on and when I got home I pulled out the code 45....RICH EXHAUST PRESENT.....Why would this happen...and what should I look for?

 

I guess the best place to start would be the wiring & connections?

 

DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich

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Not easy to diagnose. On the L98, Code 45 means that the oxygen sensor sent a voltage at .7 or above for over 50 seconds with a throttle position that's greater than 2%. Clear the code & drive the car to see if it comes back. It can be caused by anything from faulty signals from the TPS or MAF, a rich or leaking injector or too much fuel pressure, a satuated canister purge tank, a stuck egr, or faulty wiring. If it does come back, I'd start with the wiring first and make sure it's well away from any spark plug wires. Electrical interference could send a false signal. Also, the possibilty exists that some anti-seize is on the sensor, so you might want to pull it out and check for contamination. If the wiring & sensor appear ok, I'd put the old one back in just to see if the new one has gone south and you might want to try the old ECM too since you replaced it. Otherwise, it's probably best to hook up a scan tool and capture data when the code sets. Then take a close look the TPS, MAF & BLM data stream to pinpoint it further.

 

My Haynes manual says look for a vacuum leak at the EGR valve. I'm having this problem with my 92 LT1, usually in conjunction with a code 23 (IAT). This only happens when the engine gets above about 175 degrees. I don't know how it affects your engine, but mine now begins missing and backfiring above 4500, which means the Mustangs get away and the cars with the lights on top catch up. :nonod: [B]

 

Thanks for the help..I cleared the code and it has not came back yet.....I get check out some things in the morning....I may pull a few of the new plugs to se if they are fouled and look at the the new O2 sensor to check it out....