Service engine light and codes

ALAN WILLIS

MEMBER
1999 MERCURY VILLAGER
3.3L
6 CYL
2WD
AUTOMATIC
97,000 MILES

My van's SE light has come on after so many times of trying to remedy the codes, from Knock Sensor to misfiring cylinder. The thing is the car runs fine, even though there is a slight rough idle. In the past two years I replaced the distributor correct a rough timing issue. I had a faulty KS code and relocated the KS and solved the code for it. I had a code for misfire for cylinder three and replaced wires and plugs which solved the code for it. One day last November my SE light came on, ran to store and codes indicated all my previous codes listed as problem. Surprisingly, the light cleared and codes disappeared. Now two months later SE light back on and store indicates same codes from back in November. My questions are: Would a professional diagnostic indicate a faulty ECM as being the culprit of my codes and light? Or just replace the ECM without the added expense of a diagnostic? Or could there be other reasons for codes and diagnostic is definitely recommended?

Thursday, January 17th, 2019 AT 10:01 AM

3 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Good evening,

Lets back up a second.

What are the exact codes that are set?

I would not assume anything about the ECM until it can be confirmed. It is a very expensive guess as the other two repairs did not work either.

Roy

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Thursday, January 17th, 2019 AT 3:52 PM

ALAN WILLIS

MEMBER
2 POSTS

Here are the exact error codes:
P0300 Random Misfire Detected
P0325 Knock Sensor 1 Circuit Malfunction
P0300 Random Misfire Detected
P0325 Knock Sensor 1 Circuit Malfunction
P1320 Distributor Interrupt

I dealt with P0325 for a long time. I eventually solved that problem by relocating the sensor to a more easily accessible location without tearing removing engine manifold. I've replaced all the spark plugs and wires and it resolved the random misfire codes. All the codes only returned, as I previously wrote, back in November and as soon as they returned had cleared out, (I know this because it passed the state EPA's inspection soon after it cleared out. Two months later the codes returned and this time they aren't clearing out. My distributor is only three years old. My spark plugs and wires are less than a year old. My understanding from a local mechanic that it could be in the harness or a wire elsewhere causing my problem and I should investigate that before replacing the ECM. I'm going to assume you would recommend that too. Thanks for responding.

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Friday, January 18th, 2019 AT 8:55 AM

ASEMASTER6371

MECHANIC
52,796 POSTS

Okay, the 300 and 325.

325 sets when any other code is set. It has done this from the beginning for some reason. When there are no codes, 325 will not set. Factory states to ignore that code.

The 300 is a common one. I would start by checking the fuel pressure. That is the most common failure for the 300 code.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

As far as the distributor code, I would check the connector at the distributor to be sure it is clean and secure.

Roy

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Friday, January 18th, 2019 AT 9:12 AM