Vehicle Fault or Driver Fault?

Nov. 12, 2019

This bulletin applies to 2018 GMC Terrain and Acadia vehicles. The MIL may be on, with no drivability concerns. The technician may find DTC P2097 stored.

There are many things that can cause the P2097 and care must be taken when diagnosing this code. SI diagnostics for P2097 tests the purge valve and lines for concerns.

When performing the following procedures, the purge solenoid vacuum source line should be disconnected and blocked off at the intake manifold source.

With the engine at normal operating temperature and the air conditioner/defroster turned off, monitor the long term fuel trim value for five minutes under each of the following conditions:

1. Idle the engine in Park with your foot off the brake pedal.

2. Idle the engine with your foot on the brake pedal to hold the vehicle from moving and place the transmission in Drive.

3. Drive the vehicle at a steady speed of 50 mph or above without using the cruise control.

After completing the above, in the service bay with the transmission in Park, take note of the long term fuel trim value. Using the accelerator pedal, raise engine idle up to approximately 2,000 rpm and hold it there for 2 minutes and monitor any changes in the long term fuel trim value.

If the long term fuel trim value was high and then dropped into a normal range (-13% to +13%) and stays there, the concern may be a vacuum leak, skewed MAF sensor, modified/damaged air box or a non-OEM air filter. Swap as many parts from a known good vehicle to rule out specific components mentioned.

If there is no change, perform an AFIT test on all of the fuel injectors to see if any lean injectors can be found. If no individual lean injectors can be found, replace all four injectors.

If the long term fuel trim value was in a normal range and never stayed outside of the normal range, ask the customer if they drive in heavy stop and go city traffic. Drive with the customer and see if they are a digital driver. A digital driver is one who gets up to their desired speed, then lets off the throttle and lets the vehicle coast down by a few miles per hour and then gets back onto the throttle to get back up to the desired speed.

These driving habits can induce P2097. There is no fix available when the customer drives in this manner.