What this code means
P16F3 may mean the PCM is seeing a low-voltage condition on the starter cut relay 1 control circuit.
What the vehicle may do
- The vehicle may start normally while the code is stored.
- The vehicle may have an intermittent starting complaint.
- The vehicle may not start when the fault is active.
Possible fault areas
- Possible starter cut relay control circuit wiring concern.
- Possible ignition-feed or fuse-side circuit concern.
- Possible loose terminal or poor connection at the starter cut relay or PCM.
- Possible PCM software or PCM-side concern after circuit checks are completed.
Diagnostic path
Opening context
On this 2010 to 2016 Honda CR-V with the 2.4 gas engine, P16F3 is for the starter cut relay 1 control circuit reading low voltage. In plain terms, the PCM may not be seeing the starter cut relay control side behave the way it expects. The vehicle may start normally, may have an intermittent starting complaint, or may not start when the fault is active. Broadly, this can involve the starter cut relay control wire, the ignition feed through the fuse circuit, connector fit at the relay or PCM, or the PCM side after the circuit checks are clean. Before getting into the pinpoint tests, start with the basic system checks and make sure the complaint and code information make sense.
First split: does the engine start?
Start by trying to start the engine. This first check decides which side of the diagnostic path you take. If the engine starts, move into code duplication. If the engine does not start, skip ahead to the voltage check at the PCM connector.
If it starts: duplicate P16F3
If the engine starts, turn the vehicle to OFF (LOCK), then turn it back to ON. Clear the code with the HDS, then check for pending or confirmed codes with the HDS. If P16F3 comes right back, the failure is duplicated and you can test the starter cut relay 1 control wire for a short to ground. If P16F3 does not return, treat it as intermittent for now. The system is OK at this time, so concentrate on poor connections or loose terminals at starter cut relay 1 and the PCM. If captured operating data is available for this code, try to reproduce those same conditions instead of guessing.
Short check on the ST CUT RLY1 CL- line
With the failure duplicated, turn the vehicle to OFF (LOCK), remove starter cut relay 1 from the under-hood fuse/relay box, jump the SCS line with the HDS, and wait more than 1 minute. Then disconnect PCM connector A, the 51P connector. With the vehicle in OFF (LOCK), starter cut relay 1 disconnected, and PCM connector A disconnected, check continuity from PCM connector A 51P terminal No. 33 to body ground. If there is continuity, repair a short in the ST CUT RLY1 CL- wire between PCM terminal A33 and starter cut relay 1. If there is no continuity, that control wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If P16F3 goes away after the update, the troubleshooting is complete. If it goes away with a substitute PCM installed, replace the original PCM.
If it does not start: voltage check at PCM A33
If the engine did not start during the first check, turn the vehicle to OFF (LOCK), jump the SCS line with the HDS, and wait more than 1 minute. Disconnect PCM connector A, the 51P connector. Then turn the vehicle to ON and measure voltage between PCM connector A 51P terminal No. 33 and body ground. This check is done with the vehicle in ON mode and PCM connector A disconnected. If you have battery voltage there, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If P16F3 goes away after the update, you are done. If it goes away with a substitute PCM, replace the original PCM. If there is not battery voltage, continue into the open-circuit checks.
Open check on the ST CUT RLY1 CL- line
Next, turn the vehicle to OFF (LOCK), remove starter cut relay 1 from the under-hood fuse/relay box, and leave PCM connector A disconnected. Check continuity between starter cut relay 1 4P socket No. 4 and PCM connector A 51P terminal No. 33. The test condition is vehicle OFF (LOCK), PCM connector A disconnected, and starter cut relay 1 disconnected. If there is continuity, the ST CUT RLY1 CL- wire is OK and you move to the fuse check. If there is no continuity, repair an open in the ST CUT RLY1 CL- wire between PCM terminal A33 and starter cut relay 1.
Fuse check
Now check fuse No. B2 (10 A) in the under-dash fuse/relay box. If the fuse is OK, continue to the IG1 ACG open-circuit check. If the fuse is not OK, check for a short in the IG1 ACG wire between the No. B2 (10 A) fuse and starter cut relay 1, repair that short as needed, and replace the No. B2 (10 A) fuse.
Open check on the IG1 ACG line
For the last circuit check, disconnect under-dash fuse/relay box connector D, the 32P connector. Use a jumper wire from connector D 32P terminal No. 7 to body ground. With the vehicle OFF (LOCK), PCM connector A disconnected, starter cut relay 1 disconnected, under-dash fuse/relay box connector D disconnected, and terminal No. 7 jumped to ground, check continuity between starter cut relay 1 4P socket No. 3 and body ground. If there is continuity, the IG1 ACG wire is OK, so replace the under-dash fuse/relay box. If there is no continuity, repair an open in the IG1 ACG wire between the under-dash fuse/relay box and starter cut relay 1.
Verification and close
Keep the verification separate from the circuit testing. After any wiring repair, fuse replacement, PCM update, known-good PCM check, PCM replacement, or fuse/relay box replacement that was called out by the test result, clear the code and confirm P16F3 stays gone under the same operating conditions that brought it in. The takeaway is simple: follow the engine-start split first, prove the starter cut relay 1 control and ignition-feed circuits, and only move toward PCM or fuse/relay box decisions after the circuit checks support it. For more diagnostic training, visit stepdiagnostics.com.
Final check
P16F3 is often approached by first separating a starts-versus-no-start condition, then proving the relay control and ignition-feed circuits before considering module-side decisions.
For more guided automotive diagnostics, visit STEP Diagnostics.
