Scotty I have a 2009 Cadillac DTS 4.6L Automatic “vin Y” with 92300 miles
At the beginning of January 2025 I got a DTC
P0446
Evaporative Emission System Vent Control Circuit
I replaced the vent valve on the charcoal canister and cleared the code…. 2 days later I got another DTC
P0451
Evaporative Emission System Pressure Sensor/switch
I replaced the fuel tank pressure switch….
Since the repairs there have been no codes and all I/M monitors are ready. My problem is with the live data, The Purge Flow Monitor test $C5 has a high H20 reading and the Secondary Air Monitor has Low PSI. What do these readings mean!
|
Test |
$C5+ |
|
MOD |
$00 |
|
MAX |
10.04 (H20) |
|
MEAS |
-0.02 (H20) |
|
MIN |
-32.12 (H20) |
|
STS |
HI |
Secondary Air Monitor
|
|
|
|
Test |
$E1 |
|
MOD |
$00 |
|
MAX |
0.870(PSI) |
|
MEAS |
0.685(PSI) |
|
MIN |
-0.145(PSI) |
|
STS |
Low |
|
|
|
|
Test |
$E2 |
|
MOD |
$00 |
|
MAX |
8.481 (PSI) |
|
MEAS |
0.876(PSI) |
|
MIN |
-0.290(PSI) |
|
STS |
Low |
|
|
|
|
Test |
$E3 |
|
MOD |
$00 |
|
MAX |
1.624 (PSI) |
|
MEAS |
0.077 (PSI) |
|
MIN |
-2.901 (PSI) |
|
STS |
Low |
|
|
|
|
Test |
$E5 |
|
MOD |
$00 |
|
MAX |
3276.7 |
|
MEAS |
12. 7. |
|
MIN |
2.5 |
|
STS |
OK |
Secondary Air Monitor has Low PSI.
The pressures will go up and down as the EVAP system performs its functions. All values are within normal range.
As you said the diagnostics are happy, so you don't need to be concerned.
