What this code means
P1659 may indicate that the PCM is seeing an ETCS control relay OFF malfunction in the drive-by-wire throttle relay circuit.
What the vehicle may do
- The vehicle may turn on a warning light.
- Throttle response may be limited or reduced.
- The vehicle may feel like it is in a protective operating mode.
Possible fault areas
- Possible areas include the ETCS control relay.
- Possible areas include the relay fuse and power feed.
- Possible areas include relay output or relay control wiring between the relay and PCM.
- Possible areas include fuse and relay box connections or internal faults.
- PCM software or the PCM itself may be involved after the circuit checks pass.
Diagnostic path
Open on what this code is really asking us to prove
On this Honda CR-V, P1659 points toward an ETCS control relay OFF malfunction. In plain terms, the PCM may not be seeing the drive-by-wire relay circuit behave the way it expects. The vehicle may set a warning light, may limit throttle response, or may feel like it is protecting itself. The broad areas in play are the ETCS control relay, its power feed and fuse, the under-dash fuse and relay box, the relay output and control wiring back to the PCM, and in some cases PCM software or the PCM itself. Before getting deep, start with the basic system checks, then work this circuit in order.
First duplicate the fault
Start by turning the vehicle to ON mode. Use the HDS to clear the DTC, then check for Pending or Confirmed DTCs. If P1659 comes right back, the failure is duplicated and you can move into circuit testing. If it does not come back, treat it as intermittent for now. The system is OK at this moment, so look closely for poor connections or loose terminals at the ETCS control relay and the PCM. If captured operating data is available, try to make the vehicle fail again under those same conditions instead of guessing.
Check the fuse and relay before chasing wiring
With the failure duplicated, turn the vehicle to OFF (LOCK) mode and check fuse No. A22 (15 A) in the under-hood fuse and relay box. If that fuse is OK, move to the relay check. If it is not OK, the path changes toward a short check later in the routine. Next, remove the ETCS control relay from the under-dash fuse and relay box and test the relay. If the relay fails its test, replace the ETCS control relay. If the relay tests OK, continue with the socket voltage checks. If you do not have the exact relay-test details available, pause and get the correct relay test before making a call on the relay.
Check relay socket power at the under-dash box
Leave the ETCS control relay disconnected and turn the vehicle back to ON mode. Measure voltage between ETCS control relay 4P socket No. 3 and body ground. If there is no battery voltage there, the diagnostic result is to replace the under-dash fuse and relay box. If battery voltage is present, move to socket No. 1. Measure voltage between ETCS control relay 4P socket No. 1 and body ground. If there is battery voltage, continue to the relay output wire check. If there is no battery voltage, go after the +B DBW feed path next.
If socket No. 1 is missing power, check the +B DBW feed for an open
For the +B DBW open check, turn the vehicle to OFF (LOCK) mode. Disconnect under-dash fuse and relay box connector D, the 32P connector. With the vehicle still in OFF (LOCK) mode, the ETCS control relay disconnected, and connector D disconnected, measure voltage between connector D No. 5 and body ground. If battery voltage is present there, the +B DBW wire is not open, and the result is to replace the under-dash fuse and relay box. If battery voltage is not present, repair the open in the +B DBW wire between the No. A22 (15 A) fuse and the under-dash fuse and relay box.
Check the relay output wire back to the PCM
When the fuse and relay power path checks allow you to continue, turn the vehicle to OFF (LOCK) mode. Jump the SCS line with the HDS, wait more than 1 minute, and disconnect PCM connector C, the 51P connector. With the vehicle in OFF (LOCK) mode, the ETCS control relay disconnected, and PCM connector C disconnected, check continuity between PCM connector C No. 2 and ETCS control relay 4P socket No. 2. If there is continuity, the VBDBW or DBW relay output wire is OK and you move to the relay control-side wire. If there is no continuity, repair the open in that wire between PCM C2 and the ETCS control relay.
Check the relay control-side wire
Next disconnect PCM connector A, the 51P connector. With the vehicle in OFF (LOCK) mode, the ETCS control relay disconnected, PCM connector C disconnected, and PCM connector A disconnected, check continuity between PCM connector A No. 19 and ETCS control relay 4P socket No. 4. If there is no continuity, repair the open in the DBW RLY CL- wire between PCM A19 and the ETCS control relay. If continuity is good, the wiring has passed this side of the test. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM and recheck. If P1659 goes away after the update, the troubleshooting is complete. If it goes away only with the known-good PCM installed, replace the original PCM.
If the fuse was not OK, start the short checks at the relay output line
If the No. A22 (15 A) fuse was not OK, the routine moves into short-to-ground checks. Remove the ETCS control relay from the under-dash fuse and relay box. Jump the SCS line with the HDS, wait more than 1 minute, and disconnect PCM connector C, the 51P connector. With the vehicle in OFF (LOCK) mode, the relay disconnected, and PCM connector C disconnected, check continuity between PCM connector C No. 2 and body ground. If there is continuity, repair the short in the VBDBW or DBW relay output wire between PCM C2 and the ETCS control relay, and replace the No. A22 (15 A) fuse in the under-hood fuse and relay box. If there is no continuity, that output wire is OK, so continue to the +B DBW short check.
Check the +B DBW line for a short
With the vehicle in OFF (LOCK) mode, the ETCS control relay disconnected, and PCM connector C disconnected, check continuity between ETCS control relay 4P socket No. 1 and body ground. If there is no continuity, the short is not showing on that leg, so update the PCM if it does not have the latest software, or substitute a known-good PCM and recheck. If P1659 goes away after the update, troubleshooting is complete. If it goes away with the known-good PCM, replace the original PCM. If there is continuity at socket No. 1 to ground, continue to isolate the +B DBW line at the under-dash fuse and relay box connector.
Isolate the +B DBW short at connector D
Disconnect under-dash fuse and relay box connector D, the 32P connector. With the vehicle in OFF (LOCK) mode, the ETCS control relay disconnected, PCM connector C disconnected, and connector D disconnected, check continuity between connector D No. 5 and body ground. If there is continuity, repair the short in the +B DBW wire between the No. A22 (15 A) fuse and the under-dash fuse and relay box. If needed, replace the under-hood fuse and relay box, and also replace the No. A22 (15 A) fuse in the under-hood fuse and relay box. If there is no continuity, the +B DBW wire is not shorted, and the result is to replace the under-dash fuse and relay box.
Verify the repair
After the repair, keep verification separate from the circuit testing. Reconnect what was disconnected, clear the code with the HDS, and recheck for Pending or Confirmed P1659. If the fault was intermittent, try to reproduce the same captured conditions before calling it fixed. The takeaway is simple: do not condemn the PCM or a fuse box until the relay, fuse, power feed, relay output, and relay control wires have been proven in order. For more diagnostic training, visit stepdiagnostics.com.
Final check
P1659 is often a power, relay, wiring, or control-side diagnosis; prove each part of the circuit in order before making the final call.
For more guided automotive diagnostics, visit STEP Diagnostics.
