2003 Ford Windstar 420 Code

MJESIC1

MEMBER
2003 FORD WINDSTAR
3.8L
6 CYL
2WD
AUTOMATIC
200,000 MILES

We have a 420 code displayed and the O2 sensor is working properly, there is no converter rattling. Cleaned intake. Initially the code was a 401, now it's gone. But 420 code appears. What is our next step?

Tuesday, November 18th, 2014 AT 6:50 AM

4 Replies

HMAC300

MECHANIC
48,601 POSTS

This depends on whether or not you have an exhaust gas system module or not. But fords have a habit of eating up the exhaust gas sensor. It is in the pic that I have sent so that may be the problem as both use that. Otherwise it may be the module is keeping the EGR valve open. The sensor is at the lh rear of engine compt. It is also called the dpfe sensor or differential pressure feedback EGR

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Tuesday, November 18th, 2014 AT 7:09 AM

MJESIC1

MEMBER
3 POSTS

Thanks. We have already solved the egr problem (we replaced dpfe valve, vacuum regulator solenoid and removed intake and cleaned port for egr valve). But now the 420 code is coming up (02 sensor seems to be working properly by scan tool and no converter rattle). What else could be our cause?

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Tuesday, November 18th, 2014 AT 7:16 AM

HMAC300

MECHANIC
48,601 POSTS

420 is a bad converter code and with your mileage it very well cold be even if it's not rattling. There are converter clean up chemicals that you can try, don't know if they work or not however. It can also be an air leak prior to the converter but I kind of doubt it. Here are possible causes in pic but it wouldn't surprise after checking this stuff that it's the converter. A pro can freeze frame to make sure it's converter.

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