430 How does the ECU know I have a small leak?(P0442)

Depending on your assembly number... There is a diagnostics pump (251288) that knows there is a problem.

Did you remove the check valves to make sure there isn't any fuel inside? Did you remove the canister and see if the charcoal is goo from gasoline contamination?

I had this code on my 2009 and it was due to overfilling/topping off of the fuel tank where it eventually backed up into the canister and caused the need to replace the entire evap system including the check valves, canister, diagnostic pumps and hoses.

 

I believe the diagnostic pump (where applicable) has some kind of inbuilt pressure sensor.

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The system "periodically" pressurises the evap system. It has to close the evap valves to do this.

Would your smoke tester tell you if your canister purge solenoid valves were closing properly? The smoke would go into the intake manifolds.

 

Check your gas cap.

 

Unfortunately, the manual doesn't specify when these periodic diagnostic pressure tests are being done. At certain times (details unknown, but I believe after engine warmup), the evap purge valves are opened and fuel fumes are vented into the engine intake, so it would mean the diagnostic pressure tests can't be done at this time. You'd need a sealed system. I suppose startup would a good time for running the diagnostic test without interfering with the normal operation of the evap purge valves, but it doesn't necessarily exclude other times.

Looking at the suggested maintenance for this code, it's hard to say.

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Maybe the chart predates the introduction of the diagnostic pump? I think the "anti-evaporation test" they speak of is a maintenance test.

The chart suggests major leakage. You would think this would easily be spotted during a smoke test.

What is the fuel pressure sensor they speak of? Are they talking about the one built into the diagnostic pump? I can't find a pressure sensor in the parts manual.

If a purge valve was stuck open, would it generate its own code, or would the P0442 code be generated? Or would this be easily spotted on a smoke test? Maybe you could try clamping the purge valve hoses one at a time to see if the CEL still illuminates?

More questions than answers at this point. Time to get out the shotgun or time to consult the real experts?

 

So did that fix your issue?

 

sorry to hear it's persisting please keep us updated

 

Air shouldnt pass through so old one must have been defective

 

Doesn't look like it.

The diagrams don't seem to show a sensor either. See M301:

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... just a motor, valve and resistor. What the resistor does, I don't know. The Left Bank ECU seems to provide independent control of pump and valve (via pins 1 and 3). What the resistor does, I don't know. It seems to be part of the circuit which controls relay PSR8, the low speed pump relay.

Does pump operation inhibit the motor and valve?

 

I meant to say fuel pump.

I wonder if the ECU monitors the current in the evap pump. A leaky evap system would mean less load on the pump (no back pressure). Or there could be a pressure switch controlling power to the pump (inside the pump). The ECU then monitors the duty cycle of the pump.

 

I can't think of anything at the moment, but it's not specifically controlling, but monitoring. It's quite common for fault reporting (code generation) circuits to monitor a control circuit. e.g. solenoid and relay coils are monitored for shorts to power, shorts to earth, etc.

If you Google leak detection pumps, you sometimes get images of pumps with reed switches inside. Here's a description of a pump, but I'm not quite sure if the circuit requires a specific wire for the fault detection part:

https://www.liveabout.com/leak-detection-pump-ldp-4083816

You seem to be running out of options. Usually the fuel cap causes these issues, but I don't know why you didn't find the issue with your smoke check.