2002 - Suddenly get P1430 code w/Check Engine Light

Gas cap seal?

Bob Wilson

 

The second choice (HCAC vacuum sensor) is correct, the first one about some air pump is off the wall and must be about some totally other car. Where were you looking that up?

That sensor measures the vacuum in the circuit that operates the HCAC valve (in the exhaust pipe ahead of the catalytic converter). I'm not sure exactly where the sensor itself lives; page SF-50 is where you would look for the replacement instructions (but that's in my 2001 book, pages might be different for your 2003).

Pages DI-127 to DI-130 (again, 2001 edition) show the diagnostic steps to sort out the possible causes. Basically they have you measure the sensor voltage back at the ECM itself (which is easy to get to behind the glove box). If the reference voltage being supplied to the sensor by the ECM isn't right, then they'll call the ECM the culprit. Otherwise, if the sense voltage coming back is reasonable, they'll call the sensor likely good, and the ECM still the culprit. If the sense voltage is wrong coming back, they'll have you check for wiring damage on the way to the sensor first, and then only if you find no wiring problem, by elimination the sensor is what's left.

-Chap

 

Oh hey, I just looked again and you've got a 2001 also, so our page numbers should be the same. I must have glanced up and seen Bob's 2003 and thought that was what you had. Sorry for the mixup.

-Chap

 

Did you ever figure out what was wrong? I am working on this for my car right now as well. I got this code, and a cylinder misfire code (p0303) at the same time. According to Autozone, a common fix is replacing spark plugs. I replaced the plugs, but the car is running pretty rough and I am getting the misfire and p1430 code still. I have ordered new ignition coils and will try that. They probably are due for replacement either way, since they are original and I have 181k on the car.

If you were able to find something out I would love to hear what that was. Thanks.

 

Have you tried going through the workup steps on pages DI-127 to DI-130 yet? What results did you get?

Cheers,
-Chap

 

I just drove my 2001 Prius to the store and came home to P1430 and a P302 codes..after I linked my scan tool and started the car P1431 came up as a "pending code"...any ideas? Thanks guys..
It's been a great car..it has 124k miles..I drove it from California too Oklahoma a few times..I changed the spark plugs about 5k miles ago..I did let the battery die a few weeks ago but I've driven it a few times since then with no problems..

 

I have returned from the land of Mordor, and I have a suggestion regarding P1430. I had it; fault would not clear. The canister moved the HCAC valve freely when the car started, so I knew it was generating good vacuum, no leaks. So it must be electrical. What I found:
The vacuum sensor which generates this code is just above and to the left of the dipstick. It's held in place on a bracket with two M6 bolts with 10mm hex heads. The Toyota part number is 89421-20190 and says "SENSOR, VACUUM". The vacuum hose (black, about 7mm diameter) connects to the bottom of the sensor. The electrical connector is a push-to-release, and the locking tab is pretty stiff. It has 3 wires coming out - brown, violet and yellow w/red stripe. One of these wires (vellow/red) broke right at the connector and was so close, it looked like it was good - until I replaced the vacuum sensor and found only two wires still intact. So, if you are getting intermittent P1430 codes, apparently randomly, it's a possibility that the wires coming out of the vacuum sensor connector are broken and occasionally losing conductivity. The wires make a 90 degree bend right out of the connector, so they are under stress, and any big hands removing or inserting the dipstick are likely to brush against the connector and stress the wires again. I happened to have a sacrificial Prius from which I snatched a replacement connector. So I cut out the damaged connector, and soldered the wires to the new connector. Start the car, clear the code, and it goes away.
So here's the electrical check: brown wire is ground; yellow/red is +5v, and violet is (a) 3.6v at cold start (b) drops to 2.0 and 1.6 at various stages of the warm-up. Inspect the wires carefully at the vacuum sensor connection. IT IS POSSIBLE THAT THE WIRE IS BROKEN INSIDE THE INSULATION AND THE INSULATION IS INTACT. In other situations, I have seen instances of broken wires inside an intact insulating sleeve. Use a pin to puncture through the violet wire, and read the voltages as the car warms up. If the yellow wire is broken, the voltage on violet will stay at zero. If the brown wire is broken, the violet wire will read +5v. If the violet wire is broken, the voltage will be zero or some strange value less than +5v, but not the 3.6 or 2.0 or 1.6 as the vehicle expects.
The repair: I happened to have a connector. It is NOT available at Radio Shack (RIP) or its equivalent. It's Toyota robust, waterproof sealed; the sensor contacts were in very good shape. No corrosion after 17 years. So it failed just outside the connector.
You can check your work by connecting the wires to the prongs of the sensor with alligator clip jumper cables, taking care to match yellow, violet (middle) and brown appropriately, and see if the fault code can be cleared. If it clears, and stays away, you know that you found the location of the flaw.
Then what remains is a robust repair. I'm still thinking about that.
If this gets found by Toyota service, they have to replace that portion of the wiring harness. IF they can find one. Ouch.

Good luck to all who visit this thread...

 

Thanks for the detailed write-up!

-Chap

 

Following up: Toyota does sell the connector shell. HOWEVER: the shell does not contain the wires.
They have wiring repair kits... but replacing the wires in the shell requires some special tool that I don't have.
The Toyota terminal repair kit part number is 82998-12340, which is a SINGLE WIRE with one connector on it.
Each kit fits one prong in the sensor. Price is US$7.48 per kit, at my local dealer.
If you must discard the shell, you will need 3 kits to restore functionality.
Weatherproofing: heat-shrink tubing over each connector when you replace the ends.
CHECK FOR CORRECT OPERATION. Then fill the end of the sensor with RTV to make it water tight.
This is a suggestion; I haven't done it. Good luck to all.

 

Yet more followup on P1430 & P1437:
Between the vacuum valve monitor (which sets these codes) and the HCAC valve (which in some climates is prone to seizing up), there is a stretch of metallic pipe (which carries the vacuum from the manifold to the HCAC) and, connecting to the HCAC valve, a short length of 8mm OD (1/4 inch OD) rubber hose. After a number of years, this short length of hose is prone to splitting where it connects to the pipe from the sensor, which is ABOVE the HCAC and not very visible. You have to remove the hose from the car to do the inspection. The pipe from the engine has a little bulb on the end, and it's right there that the hose seems to fail by splitting. Seen this twice, now.
This hose failure appears to be the root cause of my intermittent P1430 and P1437 codes on my 2003 Prius (287k miles). Depending on which way the rubber bent, it would sometimes allow the HCAC to work correctly (the valve was determined to move freely), and sometimes not; sometimes the first code set was a "low vacuum" (P1430).
So be sure to give this little bit of hose a good looking over; particularly if you're dropping the cat converter/resonator/HCAC valve assembly for inspection and/or repair, if you have either of these codes. It's a $.50 fix to replace it with basic 1/4 in black rubber hose from the hardware or auto parts store.