Code 13

Code 13 is a diagnostic trouble code related to the oxygen sensor circuit on the Pontiac Fiero.

Code 13 indicates that the ECM has detected a problem with the oxygen sensor signal or circuit.

Overview

The oxygen sensor sends a changing voltage signal to the ECM during normal operation. The ECM uses this signal to monitor exhaust oxygen content and adjust fuel mixture during closed-loop operation.

Code 13 is set when the ECM detects no normal variation in the oxygen sensor voltage signal during normal operation.

This usually means the oxygen sensor is disconnected, the sensor circuit has a wiring or connector problem, or the oxygen sensor needs to be replaced. A sticking or misadjusted Throttle position sensor may also contribute to this condition.

Flash pattern

Code 13 is displayed as:

• One flash
• Pause
• Three flashes

This represents code 13.

Animated flash pattern:

Meaning

Code 13 indicates that the ECM is not seeing the expected variation in the oxygen sensor signal.

Possible causes include:

• Disconnected oxygen sensor
• Faulty oxygen sensor
• Oxygen sensor wiring problem
• Poor connector contact
• Exhaust leak near the sensor
• Sensor not reaching operating temperature
• Sticking or misadjusted Throttle position sensor
• ECM input problem
• Poor ground or related electrical fault

Symptoms

Possible symptoms may include:

• Check engine light
• Poor fuel economy
• Rich or lean running
• Rough idle
• Hesitation
• Failed emissions test
• Little or no obvious drivability problem

Diagnosis

Basic diagnostic checks include:

1. Confirm that Code 13 is present.
2. Inspect the oxygen sensor wiring and connector.
3. Check for exhaust leaks near the oxygen sensor.
4. Check engine grounds and related wiring.
5. Verify that the engine reaches normal operating temperature.
6. Check for other stored trouble codes.
7. Test the oxygen sensor signal if equipment is available.
8. Replace the oxygen sensor only after wiring and related causes have been considered.

Related codes

Related fuel-control and oxygen-sensor codes include:

• Code 44 - Lean exhaust indication
• Code 45 - Rich exhaust indication

Notes

The oxygen sensor must be hot enough to operate correctly. A cooling-system or thermostat problem that prevents normal operating temperature may affect closed-loop operation.

A Code 13 should be diagnosed as a circuit or signal problem, not simply as an automatic oxygen sensor replacement.

See also

• Diagnostic trouble codes
• ALDL diagnostics
• Oxygen sensor
• ECM
• Fuel system
• Ground problems
• Code 44
• Code 45