P0405: EGR Sensor A Circuit Low (Did some tests...)
04-23-2017, 10:29 AM
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P0405: EGR Sensor A Circuit Low (Did some tests...)
Hello everyone.
My 2008 Ford f150 4.6 liter v8 is throwing a trouble code "P0405: EGR Sensor A Circuit Low". I have replaced the EGR, erased the code, and it came back within a few miles. Please note that on this model, the "EGR pressure sensor" (aka: DPFE) is mounted permanently on the EGR. Also, the only other component (i am aware of) is the "vacuum regulator". Anyway, I checked the voltage to the EGR, and here are my results (NOTE: all tests are KOEO with the harness plugged into the EGR)
(1) Brown-Wire-With-Green-Stripe(This is the return to the computer) 0.41 volts.
(2) Brown-Wire-With-White-Stripe(This is the REF voltage): approximately 5 volts.
To ensure the return voltage is reaching the PCM without signal loss, i tested the voltage of the return wire just before the wire enters into the PCM harness, and sure enough, the voltage is exactly 0.41v. Of course, there's a possibility that the harness connector could be bad, however, there is no apparent method (at least to me) how to determine if there is signal loss in the harness connector itself. hmm...
OTHER TESTS:
(1) Checked the engine vacuum. At idle the vacuum is steady at around 21 inches Hg. In gear, with foot on the brake, vacuum falls to 18 inches Hg. Reeving the engine causes the vacuum to fall to 0 inches Hg.
(2) Did a compression test. The lowest compression of any cylinder after 3 revolutions is 157 PSI. The lowest after 5 revolutions is 170 PSI.
(3) Cleaned the throttle body with appropriate cleaner, installed a new throttle body gasket, and checked all the vacuum lines for leaks and/or blockages.
(4) Cleaned the MAF sensor with the special MAF sensor cleaner.
* One alarming thing i noticed inside the intake was a light coating of fresh motor oil. Not burned carbon, but _fresh_ motor oil! I replaced the PCV value about 6 months ago, so not sure what is going on here???
Any ideas?
Many thanks.
My 2008 Ford f150 4.6 liter v8 is throwing a trouble code "P0405: EGR Sensor A Circuit Low". I have replaced the EGR, erased the code, and it came back within a few miles. Please note that on this model, the "EGR pressure sensor" (aka: DPFE) is mounted permanently on the EGR. Also, the only other component (i am aware of) is the "vacuum regulator". Anyway, I checked the voltage to the EGR, and here are my results (NOTE: all tests are KOEO with the harness plugged into the EGR)
(1) Brown-Wire-With-Green-Stripe(This is the return to the computer) 0.41 volts.
(2) Brown-Wire-With-White-Stripe(This is the REF voltage): approximately 5 volts.
To ensure the return voltage is reaching the PCM without signal loss, i tested the voltage of the return wire just before the wire enters into the PCM harness, and sure enough, the voltage is exactly 0.41v. Of course, there's a possibility that the harness connector could be bad, however, there is no apparent method (at least to me) how to determine if there is signal loss in the harness connector itself. hmm...
OTHER TESTS:
(1) Checked the engine vacuum. At idle the vacuum is steady at around 21 inches Hg. In gear, with foot on the brake, vacuum falls to 18 inches Hg. Reeving the engine causes the vacuum to fall to 0 inches Hg.
(2) Did a compression test. The lowest compression of any cylinder after 3 revolutions is 157 PSI. The lowest after 5 revolutions is 170 PSI.
(3) Cleaned the throttle body with appropriate cleaner, installed a new throttle body gasket, and checked all the vacuum lines for leaks and/or blockages.
(4) Cleaned the MAF sensor with the special MAF sensor cleaner.
* One alarming thing i noticed inside the intake was a light coating of fresh motor oil. Not burned carbon, but _fresh_ motor oil! I replaced the PCV value about 6 months ago, so not sure what is going on here???
Any ideas?
Many thanks.
