Checking Engine Error Codes

The Pontiac Fiero has an Engine Control Module (ECM). It's a little computer under the arm rest that registers error codes when any of the car's sensors detect a problem. Here's a quick how-to to check the engine codes.



As you can see from the video, I have a code 15 and a code 44. You can read about Fiero engine codes on the Fiero Forum.

Here's an explanation of my two error codes:

Code 15: Coolant Sensor (high voltage)
Because the Coolant Sensor never has an infinitely high resistance, the measured voltage should always be lower than the reference voltage. If the measured voltage is the same as the reference voltage, a problem exists with the Coolant Sensor. The ECM will set this code when it detects a problem with the Coolant Sensor (or when the coolant temperature actually drops below -30°C/-22°F).

Code 44: Oxygen Sensor - Lean Exhaust
The ECM will set code 44 when the ECM detects a low voltage from the oxygen sensor and the system is operating in Closed Loop (conditions must exist for longer than 20 seconds).Check the wires of the oxygen sensor, making sure they are not in contact with the exhaust manifold.

1. Check the oxygen sensor and replace if necessary.
2. Check the MAP sensor. If the ECM detects a higher than normal vacuum then this will cause the system to go lean. Disconnect the MAP sensor. If the lean condition goes away, then a problem exists with the MAP sensor.
3. Check for lean injectors.
4. Check for fuel contamination (specifically for contamination with water).
5. Check fuel pressure. If pressure is too low, the system will be lean.
6. Check for exhaust leaks. An exhaust leak can cause air to be pulled into the exhaust and past the sensor.
7. If you have spark knock, check the EGR system.

It's probably not a problem with the oxygen sensor, since I just had that replaced. My bet is on the fuel pump. Again, I'm not an experienced mechanic, but I do know that the fuel pump is sometimes weak and the engine sometimes has a hard time staying strong. Plus, my friend Corey tipped me off. He also said there's probably a vacuum leak. Both are probably true.