What this code means
P1890 may indicate a CVT speed control system performance concern.
What the vehicle may do
- The vehicle may show a warning light.
- CVT operation may feel abnormal or limited.
- The concern can be intermittent if the monitor passes during testing.
Possible fault areas
- Possible CVT speed control system performance issue.
- Possible control-side or scan-tool-monitored CVT condition.
- Possible influence from other pending or confirmed codes.
Diagnostic path
Opening context
On this 2010-2017 Honda Accord with the 2.4 gas engine, P1890 points to the CVT speed control system. In plain terms, the control side of the CVT may be seeing a speed-control performance problem. The driver may notice abnormal CVT operation, limited response, or a warning light, but the diagnostic path here is scan-tool driven. Broadly, this can involve possible CVT control logic concerns, speed-control performance issues, or other codes influencing the test, so don’t jump straight to a part before the code is verified under the right conditions.
Before testing
Before you start, save the freeze data and any on-board snapshot with the HDS. Then start with the basic system checks and follow a structured diagnostic approach. That matters on this code because the first decision is whether P1890 is by itself or whether another pending or confirmed code is steering you somewhere else.
Initial DTC check
Turn the ignition switch to ON (II), or use the engine start/stop button to select ON mode. With the HDS, check for pending or confirmed DTCs. If any code other than P1890 is present, handle that code’s diagnostic path first. If P1890 is the only code you’re dealing with, continue into the problem verification drive.
Problem verification drive
For problem verification, keep the setup clean. Turn the ignition switch to ON (II), or select ON mode with the engine start/stop button, then clear the DTC with the HDS. Start the engine and warm it up to normal operating temperature, which is when the radiator fan comes on twice. Test-drive the vehicle in D on a flat road. Accelerate slowly until vehicle speed reaches 37 mph (60 km/h), then hold the vehicle at about 37 mph (60 km/h) for at least 60 seconds. While doing that, monitor the OBD STATUS for P1890 in the DTCs menu with the HDS.
Interpreting the problem verification result
Now make the call from the HDS result. If OBD STATUS shows FAILED for P1890, the diagnostic path calls for transmission replacement, followed by repair verification. If the HDS shows PASSED, treat it as an intermittent failure and the system is OK at this time. If the HDS shows NOT COMPLETED, the monitor did not finish, so repeat the test-drive under the required conditions instead of guessing.
Repair verification
Keep repair verification separate from the first test. Turn the ignition switch to ON (II), or select ON mode, and clear the DTC with the HDS. Start the engine and warm it up until the radiator fan comes on twice. Then test-drive in D on a flat road. From a stop, accelerate at over 0.5/8 throttle, using 1.22 V of APP sensor voltage while monitoring APP Sensor A (V) with the HDS, until the vehicle reaches 37 mph (60 km/h) for at least 18 seconds. Then keep vehicle speed at about 37 mph (60 km/h) for at least 60 seconds. Watch the OBD STATUS for P1890 in the HDS DTCs menu.
Verification result and close
If repair verification shows PASSED, the P1890 troubleshooting is complete. After that, check for any other pending or confirmed codes and handle them separately if they are present. If it shows FAILED, the troubleshooting is incomplete, so go back to the problem verification path and recheck. If it shows NOT COMPLETED, the verification did not run to completion, so meet the test conditions and check OBD STATUS again. The takeaway is simple: on P1890, confirm no other code is leading you away, reproduce the exact drive conditions, and let the HDS status decide the next move. For more diagnostic training, visit stepdiagnostics.com.
Final check
P1890 is often handled by confirming whether it is alone, reproducing the monitor conditions, and using the HDS OBD STATUS result to guide the next step.
For more guided automotive diagnostics, visit STEP Diagnostics.
