1996 Cadillac Seville Service Engine Soon Light On

  • V8
  • FWD
  • 86,000 MILES
Had message: ck emissions
Code that came up is: P1406
Manufacturer Control
Auxillary Emissions Controls

Would like to know what it means and what it takes to fix it.
After checking with computer, light went out again.
Do you
have the same problem?
Tuesday, January 26th, 2010 AT 3:04 PM

1 Reply

DTC P1406 Exhaust Gas Recirculation (EGR) Position Sensor Performance

Circuit Description
This diagnostic test checks for a malfunction in the circuitry and hardware of the Exhaust Gas Recirculation (EGR) valve. This diagnostic test runs 3 tests to check the EGR valve power and feedback circuits and controllability of the valve. If any test fails, DTC P1406 will set.

Conditions for Setting the DTC
Test Condition
Ignition voltage 11 volts or greater.

Failure Conditions
" Test 1

Closed EGR pintle position is 0.32 volts or less


Closed EGR pintle position is 3.69 volts or more.

" Test 2

Maximum change in desired EGR position is less than 0.10 volts and pintle position error is greater than 0.20 volts for 1 second.

" Test 3

Desired EGR position is 0 and EGR pintle position is 0.40 volts or more for at least 10 seconds twice.

Action Taken When the DTC Sets
" PCM disables the EGR solenoid for the ignition cycle.

" Transaxle shift adapts are maintained at current levels.

" The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

" The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

" The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

" A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

" A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.

" Use a scan tool to clear DTCs.

" Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

You probably have a sticking EGR valve.
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Tuesday, January 26th, 2010 AT 9:55 PM

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