The Chevrolet HHR employs a second-generation on-board diagnostic system that monitors and controls the entire power train. In the event of a malfunction within the engine, transmission, engine management system, fuel system or emissions system, the brain of the diagnostic system, known as the ECM, will generate a diagnostic code and trigger the check-engine light. When the light comes on, this is your signal to have the HHR tested to read the code(s) as the first step in diagnosing and repairing the issue.
Sit down in the HHR's driver seat with the code reader, pen and paper. Look under the driver's side dashboard for the diagnostic port, a small rectangular-shaped connection port that somewhat resembles a computer printer cable end.
Plug the code reader's data-link cable into the HHR's diagnostic port. Put the HHR's ignition key in the ignition and turn it to the run position.
Follow the code reader's specific operating guide for performing a quick test on your HHR's ECM. Follow the prompts on the code reader's LED screen to read the code(s) from the ECM.
Write down the code(s) with your pen and paper.
Complete the quick test per your code reader's specific operator's guide. Disconnect the data-link cable from the diagnostic port and shut off the ignition.
