Ultimate Guide to Pontiac OBD-II Trouble Codes & Diagnostic Help

When your Pontiac’s Check Engine light comes on, it’s not just a mystery warning – it’s a signal that your vehicle is trying to tell you something. Pontiac OBD/OBD2 codes hold the key to understanding what’s going on under the hood.

By accessing these codes, you’ll gain insight into issues affecting your vehicle’s performance, from fuel and air metering problems to engine misfires. But what do these codes really mean, and how can you use them to get your Pontiac running smoothly again? You’re about to find out.

Understanding OBD-II Codes

In today’s modern vehicles, a self-diagnostic system is integrated to help identify and report specific component issues.

This system uses Diagnostic Trouble Codes (DTC) to indicate problems, which are categorized into four subsets: powertrain, network and integration, body, and chassis.

As you search for OBD-II codes, you’ll find that P codes, related to the powertrain system, are the largest category.

These codes provide specific information on troubled vehicle systems or circuits, such as fuel and air metering, fuel injector circuit issues, engine misfiring, and auxiliary emissions controls.

When searching for codes, you can use scan tools or code readers to access the on-board diagnostic system and retrieve the codes, which can then be looked up online or in repair manuals.

Reading and Interpreting Codes

When you’re dealing with a Pontiac from 1981-1995, reading and interpreting codes requires a specific approach.

To access the Diagnostic Trouble Code, turn the ignition key on without the vehicle running and jump the two right-hand ALDL terminals (A to B), forcing the ECM into a diagnostic mode. The Check Engine or Service Engine Soon light will flash, displaying each code in a series of flashes followed by a pause, and then a second series of quick flashes.

Be cautious not to simply replace the sensor referenced by the trouble code, as GM designed these codes to indicate circuit problems, not sensor issues.

If the system is loaded with codes, it usually indicates a ground problem.

Gently tapping on the ECM with your fist and noting any changes in engine performance can help diagnose issues related to ignition timing or other vehicle system problems.

Troubleshooting and Resources

You’ll need the right tools and resources to effectively troubleshoot and diagnose issues with your Pontiac’s onboard diagnostics system.

Using a scan tool or code reader, you can retrieve Diagnostic Trouble Codes and live data from a module.

For 1981-1995 Pontiacs, plug into the ALDL connector underneath the dash. Turn the ignition key on without the vehicle running and jump the two right-hand ALDL terminals (A to B) to force the ECM into diagnostic mode.

Pontiac OBD/OBD2 codes provide specific information on the troubled vehicle system or circuit.

For transmission issues, Kelley Blue Book offers resources, including searching OBD-II codes by P, B, C, or U codes and checking for safety recalls using the vehicle’s VIN or license plate number.

Most Common Pontiac OBD-II Trouble Codes