What this code means
P2135 may indicate that the PCM is seeing throttle position information that does not agree as expected.
What the vehicle may do
- The vehicle may have reduced throttle response.
- The vehicle may enter a limited power strategy.
- The code may be intermittent and may not reset during every check.
Possible fault areas
- The throttle body may be involved.
- Throttle body or PCM connector issues can be possible.
- THL1 and THL2 circuit problems may be involved.
- PCM software or PCM-side concerns can be possible.
Diagnostic path
Opening context and setup
On this Accord, P2135 is a throttle correlation code. In plain terms, the PCM may be seeing throttle position information that does not agree the way it expects. The vehicle may have reduced throttle response, may go into a limited power strategy, or may simply store the code with an intermittent complaint. Broadly, the possible fault areas can include the throttle body, the throttle body connector, the THL1 and THL2 circuits, PCM connections, or PCM software. Before getting into the diagnosis, save the freeze data and any on-board snapshot, then start with the basic system checks. Also, when the ignition is on, keep your fingers out of the installed throttle body. If the throttle valve activates, it can seriously injure your fingers.
Verify the code and duplicate the fault
Start by turning the ignition ON, or selecting ON mode with the engine start/stop button. Clear the code with the HDS, then run the ETCS test from the inspection menu. After that, check the HDS for pending or confirmed codes. If P2135 comes right back, the failure is duplicated and you move into the throttle body operation check. If P2135 is not indicated, treat it as an intermittent at this point. The system is OK right now, so concentrate on poor connections or loose terminals at the throttle body and the PCM.
Check throttle valve movement
Next, turn the ignition OFF, then disconnect the intake air duct from the throttle body. Turn the ignition back ON, clear the code with the HDS, and watch the throttle valve operation. Again, keep hands and fingers clear of the throttle bore while the ignition is on. The question here is simple: does the valve temporarily move to the fully closed position? If it does, the directed repair is to replace the throttle body, then verify the repair. If it does not move to the fully closed position, continue into the circuit and PCM side of the diagnosis.
Separate PCM-side concern from the rest of the circuit
With the ignition OFF, jump the SCS line with the HDS and disconnect PCM connector B, the 51P connector. Now check continuity between PCM connector B terminal No. 46, the RED/BLK THL1 circuit, and PCM connector B terminal No. 47, the RED/BLU THL2 circuit. If there is continuity, keep following the short check at the throttle body connector. If there is no continuity, the path is to update the PCM if it does not have the latest software, or substitute a known-good PCM, then verify the repair.
Check for a short between THL1 and THL2
For the next check, disconnect the throttle body 6P connector. With PCM connector B still disconnected and the ignition OFF, check continuity again between PCM connector B No. 46 on the RED/BLK THL1 line and PCM connector B No. 47 on the RED/BLU THL2 line. If there is continuity now, repair the short between the THL1 and THL2 wires between PCM terminals B46 and B47, then verify the repair. If there is no continuity, the THL1 and THL2 wires are considered OK by this path, and the directed repair is to replace the throttle body, then verify the repair.
Verify the repair
Keep verification separate from the testing. Turn the ignition OFF, reconnect all connectors, and exit SCS mode with the HDS. Turn the ignition ON, reset the PCM with the HDS, and do the PCM idle learn procedure. Then check again for pending or confirmed codes with the HDS. If P2135 is still indicated, recheck for poor connections or loose terminals at the throttle body and the PCM. If the PCM was updated, substitute a known-good PCM and recheck. If the PCM was substituted, go back and rerun the diagnostic path from the beginning. If P2135 is not indicated, troubleshooting for this code is complete. If the PCM was only substituted during testing, replace the original PCM. If other codes are present, check what they mean first.
Closing takeaway
The key with P2135 is not to guess at the throttle body first. Duplicate the code, confirm throttle movement, separate the THL1 and THL2 circuit check from the PCM path, and then verify that the code stays gone after the repair. For more diagnostic training, visit stepdiagnostics.com.
Final check
Follow the plausibility path in order: duplicate the fault, check throttle movement, test the THL1 and THL2 relationship, and verify the repair.
For more guided automotive diagnostics, visit STEP Diagnostics.
