Cliff: Created page with "'''Code 45''' is a diagnostic trouble code related to a rich exhaust indication on the Pontiac Fiero. Code 45 indicates that the ECM is seeing an oxygen sensor signal that suggests the engine is running rich. == Overview == The Oxygen sensor monitors oxygen content in the exhaust. The ECM uses this signal to adjust fuel mixture during closed-loop operation. Code 45 is set when the ECM detects a rich exhaust condition for longe..."

2026-07-06T19:03:04Z

Created page with "'''Code 45''' is a diagnostic trouble code related to a rich exhaust indication on the Pontiac Fiero. Code 45 indicates that the ECM is seeing an oxygen sensor signal that suggests the engine is running rich. == Overview == The Oxygen sensor monitors oxygen content in the exhaust. The ECM uses this signal to adjust fuel mixture during closed-loop operation. Code 45 is set when the ECM detects a rich exhaust condition for longe..."

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'''Code 45''' is a [[Diagnostic trouble codes|diagnostic trouble code]] related to a rich exhaust indication on the [[Pontiac Fiero]].

Code 45 indicates that the [[ECM]] is seeing an oxygen sensor signal that suggests the engine is running rich.

== Overview ==

The [[Oxygen sensor]] monitors oxygen content in the exhaust. The ECM uses this signal to adjust fuel mixture during closed-loop operation.

Code 45 is set when the ECM detects a rich exhaust condition for longer than expected. A rich indication can be caused by too much fuel, too little air, excessive fuel pressure, leaking injectors, a sensor problem, or an electrical issue.

== Flash pattern ==

Code 45 is displayed as:

* Four flashes
* Pause
* Five flashes

This represents code '''45'''.

'''Animated flash pattern:'''

[[File:Code45.gif|none]]

== Meaning ==

Code 45 usually indicates that the ECM sees the exhaust mixture as too rich.

Possible causes include:

* Faulty oxygen sensor
* Oxygen sensor wiring problem
* Excessive fuel pressure
* Leaking fuel injector
* Faulty fuel pressure regulator
* Restricted air intake
* Dirty air filter
* MAP sensor problem
* Coolant temperature sensor problem
* Manifold air temperature sensor problem
* Poor ground or connector problem
* ECM input problem

== Symptoms ==

Possible symptoms may include:

* Check engine light
* Poor fuel economy
* Black exhaust smoke
* Fuel smell
* Rough idle
* Fouled spark plugs
* Hesitation
* Poor acceleration
* Failed emissions test
* Little or no obvious drivability problem

== Diagnosis ==

Basic diagnostic checks include:

# Confirm that Code 45 is present.
# Inspect the oxygen sensor wiring and connector.
# Check for other stored trouble codes.
# Check fuel pressure.
# Inspect the fuel pressure regulator.
# Check for leaking injectors.
# Inspect the air intake and air filter.
# Check MAP sensor vacuum and wiring.
# Check coolant temperature sensor readings if possible.
# Check manifold air temperature sensor readings if possible.
# Check grounds and ECM connections.

== Fuel pressure and injectors ==

Excessive fuel pressure, a leaking injector, or a faulty fuel pressure regulator can cause a rich condition.

Related topics:

* [[Fuel pressure test]]
* [[Fuel pressure regulator]]
* [[Fuel injectors]]
* [[Fuel pump problems]]
* [[Fuel system]]

== Sensors ==

Incorrect sensor information can cause the ECM to command too much fuel.

Related topics:

* [[Oxygen sensor]]
* [[Coolant temperature sensor]]
* [[Manifold air temperature sensor]]
* [[MAP sensor]]
* [[Code 13]]
* [[Code 14]]
* [[Code 15]]
* [[Code 23]]
* [[Code 25]]
* [[Code 33]]
* [[Code 34]]

== Related codes ==

Related fuel-control and oxygen-sensor codes include:

* [[Code 13]] - Oxygen sensor circuit
* [[Code 44]] - Lean exhaust indication

== Notes ==

Code 45 should not automatically be treated as a failed oxygen sensor. Fuel pressure problems, leaking injectors, sensor faults, wiring faults, and ECM input problems can all cause a rich indication.

Diagnosis should determine whether the engine is actually running rich or whether the ECM is receiving a misleading signal.

== See also ==

* [[Diagnostic trouble codes]]
* [[ALDL diagnostics]]
* [[Oxygen sensor]]
* [[Fuel pressure test]]
* [[Fuel system]]
* [[Fuel injectors]]
* [[ECM]]
* [[Code 13]]
* [[Code 44]]

[[Category:Fieropedia]]
[[Category:Diagnostics]]
[[Category:Electrical system]]
[[Category:Engine]]
[[Category:Fuel system]]

Code 45 - Revision history