PO443 code

guitar42May 11, 2008

Hello,

I have a '97 Ford Ranger whose check engine light came on

a few days ago. I have a diagnostic code reader so I was able to turn the check engine light off but it came back on after a day or so indicating there is a prob. I read code "PO443" which points to a "evaporative emission control sytem purge control circuit malfunction". I looked at the emissions lable on the truck and it shows 1. the evap. canister 2. a purge solenoid 3. a thermistor all leading into intake manifold. On the other side of the intake manifold and on a separate hose line is the pcv valve. Before I start playing, "guess again", which part would anyone be willing to bet could be faulty thus setting this code? I also don't think the hose lines or anything is leaking.

Thank You. :)

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john_g

"97 Ford Ranger whose check engine light came on
a few days ago. I have a diagnostic code reader so I was able to turn the check engine light off but it came back on after a day or so indicating there is a prob."

What engine, trans, ect? I'll "assume 4.0l auto.

Just erasing the code and turning the lamp off is a bad habit. The testing that the PCM does as it evaluates the system can be broken down into individual tests, and a technician with the right scan tool can retrieve this information and use it to help determine what the failure is. When you clear codes, you erase all of those stored test results.

"I read code "PO443" which points to a "evaporative emission control sytem purge control circuit malfunction"."

That would be correct. The PCM when testing opens the purge valve to 75% duty cycle, and the watches for purge flow through the purge flow sensor.

1. the evap. canister 2. a purge solenoid 3. a thermistor all leading into intake manifold.

Your going to need much more than just the underhood decal for this.

"On the other side of the intake manifold and on a separate hose line is the pcv valve.

Forget the PCV, it has nothing to do with the code.

"Before I start playing, "guess again","

A wise choice, guessing can make you spend more money on things that are not bad, than having it diagnosed and repaired by a pro will.

"which part would anyone be willing to bet could be faulty thus setting this code?"

I'm willing to bet this is a bad idea, no better than you guessing yourself. The purge valve could be faulty, the purge flow sensor is a common failure, there could be a failed vent solenoid, the cannister could be plugged with dirt, there could be a wiring harness issue, a spiderweb (bug) in the hose in the rear of the truck, or the PCM itself could be at fault.

"I also don't think the hose lines or anything is leaking."

But did you test? The kinds of pratices people used to go by where they take a symptom (X) and it's always part (Y) will leave you replacing parts that are not bad, and potentially make what should have been an easy repair for a technician (fixing a car that broke) into a nightmare, (fixing a car that broke, and then had problems added to it).

You need a scan tool that can read serial data, not just a code puller. You will need bi-directional control capability through the scan tool to assist in testing components. You need to retrieve Mode $06 data to see exactly what the data reported when the test that the PCM runs failed. You will need a service manual, TSB's (There is about a twenty pager on evap systems like yours) and then you will be prepared to work your way through this.

Oh, a smoke machine helps with a flow meter, but because of this particular failure is likely not needed this time, but is needed for other evap system problems.

    Bookmark   May 12, 2008 at 8:30AM
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lolyle1_aol_com

this code came up on testing a 1996 chevy impala please offer any suggestions in regards to price and how to fix problem.

thanx

    Bookmark   April 29, 2011 at 8:34PM
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