What this code means
P0045 may indicate a turbocharger wastegate control actuator circuit fault where the PCM can see actuator current outside the expected range.
What the vehicle may do
- The vehicle may have reduced boost or weak acceleration.
- The check engine light may be on.
- The engine may feel like it is in a limited-power strategy.
Possible fault areas
- A possible turbocharger wastegate actuator issue may be involved.
- The actuator connector or wiring can be involved.
- The PCM may be considered only after the actuator and circuit checks are normal.
Diagnostic path
Opening and code logic
On this Civic 1.5 turbo, P0045 is tied to the turbocharger wastegate control actuator circuit. In plain terms, the PCM is watching the electric wastegate actuator current, and if that current is out of the specified range, it sets the code. The vehicle may have reduced boost, poor acceleration, or a warning light, and the broad fault areas can include the wastegate actuator itself, the actuator wiring, connector issues, or, after the rest of the checks pass, a possible PCM fault. Start with the basic system checks and follow a structured diagnostic approach before going into pinpoint testing.
Confirmation procedure
First, confirm the fault under the commanded wastegate test path. Start the engine. Then hold engine speed at 3,000 rpm with no load. On a CVT, use P or N; on a manual transmission, use neutral. Keep it there until the radiator fan comes on, then let the engine idle for 2 minutes. After that, run the HDS Electric Waste Gate function. This keeps the diagnostic focused on the commanded actuator circuit instead of guessing from symptoms alone.
Actuator component inspection
Next, move to the turbocharger wastegate control actuator component check. Disconnect the turbocharger 5P connector. With the connector disconnected and IG Mode OFF, check the actuator internal circuits using the turbocharger 5P connector male terminals and the correct terminal identification for the test being performed. One internal check should read About 1.2 Ω - 1.0 kΩ. The next internal checks should be Not shorted. If this component inspection is abnormal, the diagnostic points to a problem with the turbocharger assembly area rather than continuing straight to the PCM.
Prepare for circuit inspection
If the actuator checks do not identify the fault, move into the WGMTR1 positive and WGMTR2 negative circuit checks. Before disconnecting the PCM connector, jump the SCS line with the HDS and wait more than 1 minute. Then disconnect the turbocharger 5P connector and PCM connector E, 80P. This setup protects the diagnostic path and lets you test the wiring between the actuator connector and the PCM connector with IG Mode OFF.
Open and short checks on WGMTR circuits
Now check the two actuator motor circuits. For the WGMTR1 positive open-wire inspection, use the disconnected turbocharger 5P connector female terminals and disconnected PCM connector E, 80P, female terminals with IG Mode OFF. Normal is There is less than 1 Ω. Do the same style of open-wire inspection for WGMTR2 negative; normal is also There is less than 1 Ω. Then check WGMTR1 positive to WGMTR2 negative for a wire-to-wire short with IG Mode OFF. Normal is There is more than 1 MΩ. For the short-to-ground portion, use the proper open and short inspection method for the circuit you are on, then check WGMTR1 positive and WGMTR2 negative to ground with IG Mode OFF. Both should be Not shorted. If any of these wiring checks are abnormal, the diagnostic points to a problem in the circuit.
PCM conclusion and verification
If the actuator component inspection is normal and the WGMTR1 and WGMTR2 circuit inspections are normal, the remaining conclusion in this diagnostic path is a problem with the PCM. Keep that conclusion separate from repair verification. After the repair decision is made and the work is completed, verify the repair and confirm the code stays gone under the same basic operating and commanded wastegate conditions.
Takeaway and CTA
The key on P0045 is to stay in order: confirm the commanded wastegate fault, check the actuator internally, prove the two motor circuits for opens and shorts, and only then make the PCM call if everything else tests normal. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis is often about proving the commanded wastegate actuator circuit before making any module-level conclusion.
For more guided automotive diagnostics, visit STEP Diagnostics.
