EVAP System Monitor Component Checks (2018): Notes
Additional malfunctions that are identified as part of the evaporative system integrity check are as follows:
The Canister Purge Valve (CPV) output circuit is checked for opens and shorts (P0443)
that a stuck closed CPV generates a P0455, a leaking or stuck open CPV generates a P1450.
| DTCs | P0443 - Evaporative Emission System Purge Control Valve "A" Circuit |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | 5 seconds to obtain smart driver status |
| P0443 (CPV): open/shorted at 0 or 100% duty cycle |
The Canister Vent Solenoid output circuit is checked for opens and shorts (P0446), a stuck closed CVS generates a P1450, a leaking or stuck open CVS generates a P0455.
| DTCs | P0446 - Canister Vent Solenoid Circuit |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | 5 seconds to obtain smart driver status |
| P0446 (Canister Vent Solenoid Circuit): open/shorted |
The Evap Switching Valve (EVAPSV) output circuit is checked for opens and shorts (P2418).
| DTCs | P2418 - Evap Switching Valve Circuit |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | 5 seconds to obtain smart driver status |
| P2418 (Evap Switching Valve Circuit): open/shorted |
The Fuel Tank Pressure Sensor input circuit is checked for out of range values (P0452 short, P0453 open), noisy readings (P0454 noisy) and an offset (P0451 offset).
that an open power input circuit or stuck check valve generates a P1450.
| FTP volts = [ Vref * (0.14167 * Tank Pressure) + 2.6250 ] / 5.00 | ||
| Volts | A/D Counts in PCM | Fuel Tank Pressure, Inches H 2 O |
| 0.100 | 20 | -17.82 |
| 0.500 | 102 | -15.0 |
| 1.208 | 247 | -10.0 |
| 2.625 | 464 | 0 |
| 3.475. | 712 | 6.0 |
| 4.750 | 973 | 15.0 |
| 4.90 | 1004 | 16.06 |
| DTCs | P0452 - Fuel Tank Pressure Sensor Circuit Low P0453 - Fuel Tank Pressure Sensor Circuit High P0454 - Fuel Tank Pressure Sensor Intermittent/Erratic (noisy) |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | 5 seconds for electrical malfunctions, 10 seconds for noisy sensor test |
| P0452 (Fuel Tank Pressure Sensor Circuit Low): < -17.82 in H2
O P0453 (Fuel Tank Pressure Sensor Circuit High): > 16.06 in H2 O P0454 (Fuel Tank Pressure Sensor Circuit Noisy): > open circuit, short circuit or > 4 in H2 O change between samples, sampled every 100 msec |
| DTCs | P0451 - Fuel Tank Pressure Sensor Range/Performance (offset) |
| Monitor execution | once per driving cycle |
| Monitor Sequence | No P0443 or P1450 DTCs |
| Sensors OK | not applicable |
| Monitoring Duration | < 1 second |
| Entry Condition | Minimum | Maximum |
| Ignition key on, engine off, engine rpm | 0 rpm | |
| Purge Duty Cycle | 0% | |
| Engine off (soak) time | 4 - 6 hours | |
| Fuel Tank Pressure Sensor Variation during test | 0.5 in H2 O | |
| Battery Voltage | 11.0 volts |
| Fuel tank pressure at key on, engine off is 0.0 in H2 O +/- 2.0 in H2 O |
The Fuel Level Input is checked for out of range values (opens/ shorts). The FLI input is obtained from the serial data link from the instrument cluster. If the FLI signal is open or shorted, the appropriate DTC is set (P0462 circuit low and P0463 circuit high).
Vehicles with a "saddle tank" (a tank that wraps over the axle) have two fuel level senders. The FLI input is obtained from the serial data link from the instrument cluster. If the FLI signal is open or shorted, the appropriate DTC is set (P2067 circuit low and P2068 circuit high). A "jet pump" pumps fuel from the passive side of the saddle tank (Sensor B) to the active side of the saddle tank (Sensor A) where the main fuel pump supplies the engine with fuel. This means that the active side of the fuel tank typically has a high fuel level reading because it is constantly filled by the jet pump. For purposes of computing vehicle fuel level, the two FLI readings are averaged together into one signal that represents the combined fuel level.
Finally, the Fuel Level Input is checked for noisy readings. If the FLI input continues to change > 40% between samples, a P0461 or P2066 DTC is set.
| DTCs | P0461 - Fuel Level Sensor A Circuit Noisy P0462 - Fuel Level Sensor A Circuit Low P0463 - Fuel Level Sensor A Circuit High P2066 - Fuel Level Sensor B Circuit Noisy P2067 - Fuel Level Sensor B Circuit Low P2068 - Fuel Level Sensor B Circuit High |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | 30 seconds for electrical malfunctions, |
| P0460 or P0462 (Fuel Level Input Circuit Low): < 5 ohms (< 1 A/D count) P0460 or P0463 (Fuel Level Input Circuit High): > 200 ohms (>253 A/D counts) P0461 or P2066 (Fuel Level Input Noisy): > 40% change between samples, > 100 occurrences, sampled every 0.100 seconds |
The FLI signal is also checked to determine if it is stuck. "Fuel consumed" is continuously calculated based on PCM fuel pulse width summation as a percent of fuel tank capacity. (Fuel consumed and fuel gauge reading range are both stored in KAM and reset after a refueling event or DTC storage.) If the there is an insufficient corresponding change in fuel tank level, a P0460 DTC is set. Different malfunction criteria are applied based on the range in which the fuel level sensor is stuck.
In the range between 15% and 85%, a 30% difference between fuel consumed and fuel used is typical. The actual value is based on the fuel economy of the vehicle and fuel tank capacity.
In the range below 15%, a 40% difference between fuel consumed and fuel used is typical. The actual value is based on reserve fuel in the fuel tank and the fuel economy of the vehicle.
In the range above 85%, a 60% difference between fuel consumed and fuel used is typical. The actual value is based on the overfill capacity of the fuel tank and the fuel economy of the vehicle. Note that some vehicles can be overfilled by over 6 gallons.
For saddle tanks that use two fuel senders, P25B0 is set for Fuel Sensor A stuck, P25B1 is set for Fuel Sensor B stuck and P25B2 is set for Fuel Sensor A or B stuck. The active side of the fuel tank typically has a high fuel level reading because it is constantly filled by the jet pump while the passive side changes as fuel is consumed. The level of the active tank will decrease after the fuel in the passive side is consumed. To help identify a stuck sensor faster, vehicles decels and accels are used to identify the absence of movement in the FLI signal when it was expected to move due to fuel slosh.
| DTCs | P0460 - Fuel Level Input Circuit Stuck or P25B0 - Fuel Level Sensor "A" Stuck P25B1 - Fuel Level Sensor "B" Stuck P25B2 - Fuel Level Sensor "A" or "B" Stuck |
| Monitor execution | continuous |
| Monitor Sequence | None |
| Sensors OK | not applicable |
| Monitoring Duration | Between 15 and 85%, monitoring can take from 100 to 120 miles to complete |
| P0460/P25B0/P25B1/P25B2 (Fuel Level Input Stuck): Fuel level stuck at greater than 90%: > 60% difference in calculated fuel tank capacity consumed versus change in fuel level input reading Fuel level stuck at less than 10%: > 30% difference in calculated fuel tank capacity consumed versus change in fuel level input reading Fuel level stuck between 10% and 90%: > 25% difference in calculated fuel tank capacity consumed versus change in fuel level input reading |
The Evap Monitor Microprocessor is checked for proper microprocessor operation or loss of CAN communication with the main microprocessor (P260F). Applies only if EONV is in separate microprocessor.
| DTCs | P260F - Evap System Monitoring Processor Performance |
| Monitor Execution | continuous |
| Monitor Sequence | None |
| Sensor OK | not applicable |
| Monitoring Duration | 5 seconds |