Check Engine P1433

Did you mean P1443 perhaps? P1433 is "A/C refrigerant temperature circuit low"

P1443 is very common on 96~97 cars - their evaporative emissions systems are a little overly sensitive and it doesn't take much to set it off.

I replaced the purge valve/solenoid on mine several years ago and that kept it happy for a couple of years but then it started coming back again. I found some of the hoses were cracked and rotting and a replacing all of them took care of it and it hasn't been back since - age, heat and gas vapors take their toll on the hoses.

A gas cap that isn't sealing properly is also another common culprit. Make sure the sealing surface is clean and not damaged.

There's a vacuum hose that connects to a fitting low on the back of the upper intake plenum that goes to the purge flow sensor behind the intake near the firewall. From there, a hose goes to the purge solenoid by the strut tower on the passenger side and then a hose goes from the solenoid, through the fender and to the canister behind fender - you have to remove the inner fender liner to get to the canister.

Inspect all the hoses for cracks, splits and rotting but they probably need to be replaced anyway given the car's age.

Make sure the flow sensor passes air - I can't remember for sure but there may be a check valve in it so it may only flow in one direction (from intake side to solenoid side).

The solenoid can be tested by making sure it opens and passes air through it with 12V applied to it, it should hold a vacuum without voltage applied.

It's unlikely the canister would need to be replaced unless it was physically damaged.

Size vacuum hose?

Do you happen to know (off the top of your head) the size of the vacuum tubing that interconnects the purge valve/cannister/solenoid? Is the tubing all the same size?

I've been getting the P1443 (98 GT) for a couple of months now, so I thought I would start by replacing the vacuum lines first.

Do you happen to have some location pics of the purge parts?

Is the purge valve located towards the back of the manifold, near the firewall, and the purge solenoid installed by the passenger strut tower?

Thanks!

I no longer own my 96, so I can help you with pictures or the like. But, the EVAP line is very easy to find. It is a sizeable (1/4" I think), line coming from the rear plenum/throttle body going towards the firewall. It is almost always one of the messiest lines that will leave your hands covered with black residue.

Follow it back. It will connected to the evap purge sensor and the solenoid. I do not remember the order. The solenoid is larger canister whereas the flow sensor is smaller.

From my own experience, diagnosing EVAP problems on this model year Mustang can be a PIA. Problems with the solenoid and flow sensor present in the same way. Both parts go bad in almost as frequently as the other.

The solenoid can be functionally tested. It should block flow with no power. Allow flow when power applied. So if this were my car, start 1st with a functional test of the solenoid.

Next, I would replace the flow sensor. It is not very expensive. It could save you a world of frustration starting with a known good sensor.

In my case, I made the mistake of getting replacement parts from a salvage yard. One of the replacement parts (the sensor) was bad as well. What killed me was the extream time it took to complete a driving cycle after any repair was made. I wasted TONS of time trying this and that.

When ever possible, get new sensors.

Excellent methodology, WMBurns!

Thanks for the input!

Here's what I'm planning to do:

1) replace ALL EVAP vacuum lines (they are 13 years "young")
2) test the solenoid. Which side (direction) of the solenoid should allow vacuum to flow...going towards the valve or towards the cannister?
2a) if bad, replace solenoid
3) if I'm still getting the code, replace the valve.

Anyone have any luck cleaning the solenoid or valve? I've seen a couple of posts that indicate you can use carb cleaner on both....

The solenoid is not a check valve. It is on or off. I would still put it back together they way it came for hose routing reasons.

Good luck cleaning it. ESP consider how rough on rubber parts fuel vapors really are. If it is OK with you, I reserve the right to remain skeptical.

Granted!

wmburns said:

If it is OK with you, I reserve the right to remain skeptical.

Click to expand...

Perfectly fine! I'm not big on "told you so"....