Having problems with your 2002 Saturn VUE ?

Have 2002 vue with po421,po431,po171,po174 - 2002 Saturn VUE

Posted / edited by AnonymousUser on : 18-06-2018

Answers :

Okay, both catalytics are not operating efficiently, especially during warmup. Those are Codes 421 and 431.

The other 2 Codes are for lean mixtures on both banks. This means the engine is going to try to enrichen the fuel mix to compensate for the lean condition.

This is creating a problem in the catalytics as more fuel is dumping into the engine.

Once you find the source of the lean mix, the catalytics have the ability to heal or burn off the excess over time if they are not damaged.

Usually, a loose or bad fit on the Intake manifold gasket is the problem. Using a spray bottle of water, with the engine running, lightly mist the seams of the intake. Continue to vacuum fittings, vacuum lines, and on the intake manifold itself.

You should find a problem when the engine RPM changes or stalls. Then fix the leak you have found.

Other than this test, only a better scanner can help you. The most expensive scanners have an Algorithm which predicts, in order of importance, the most likely bad part. Go to a repair shop for this diagnosis, then decide if it is easier to pay them to fix it or do it yourself.
With the best scanners, you will have to pay for the diagnosis.

Autozone, Advance, and Oreilys, give free scans. You would have to call to find out if their scanner can make parts predictions.

I suspect it is a problem in the main throttle, air horn area since both sides of the motor are having the same problem.

I hope this helps you.
Repair Help & Product Troubleshooting for 2002 Saturn VUE

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