What this code means
P16E8 may indicate that the PCM is not receiving the expected shutter grille signal over a LIN communication path.
What the vehicle may do
- The vehicle may turn on a warning light.
- The active shutter grille system may not operate as expected.
- The driver may not notice a major drivability change.
Possible fault areas
- Possible power or ground circuit issue
- Possible LIN communication circuit issue
- Possible shorted component on the LIN circuit
- Possible shutter grille fault area
- Possible PCM fault area after other checks are normal
Diagnostic path
Open and frame the code
On this Honda CR-V, P16E8 is a PGM-FI code for the PCM not receiving the shutter grille signal properly over the LIN communication path. The driver may only notice a warning light, but the active shutter grille system may not be operating the way the PCM expects. Broadly, this can involve the shutter grille circuit, power and ground, the LIN line, another component tied into that LIN circuit, or, after the rest checks good, the PCM. Start with the basic system checks and follow a structured diagnostic approach. If other codes are present, use them as context first, because they can change which branch of this test path makes the most sense.
Confirm the condition and choose the path
Begin the confirmation by turning the vehicle to ON mode and waiting 10 seconds. Then check whether the related LIN or shutter-grille code is also present. Do not read a long code list into the diagnosis; just use that related-code status to decide the path. One path keeps you on the shared external circuit checks. If the related code is present, you also inspect the components connected to the LIN circuit. If it is not present, the path moves toward the shutter grille checks, and then the PCM only after the other inspection items are normal.
Prepare for the external circuit inspection
For the external circuit inspection, key off, then disconnect the shutter grille 4-pin connector, PCM connector A 50-pin, the alternator 1-pin connector, the 12 volt battery sensor 2-pin connector, and DC-DC converter connector A 3-pin. Before disconnecting the PCM connector, jump the SCS line with the scan tool and wait more than 1 minute. From here, inspect the power feed, the LIN line, and ground in order. The connector views and exact test points have to be correct for the vehicle in front of you, so do not guess at terminal locations.
Check power, LIN continuity, ground, and short-to-ground
With the shutter grille connector and PCM connector A still disconnected, and IG mode OFF, inspect the +B_FR_FOG circuit. A normal result is 12 V battery voltage. Next, inspect the LIN battery-sensor circuit for an open. Normal is less than 1 Ω. Then inspect the ground circuit for an open. Normal is also less than 1 Ω. After that, still with IG mode OFF, inspect the LIN battery-sensor circuit for a short to ground. Normal is more than 1 MΩ. If any of these circuit checks are abnormal, treat it as a circuit problem. If the power supply check is the one that failed, continue with the added power supply inspection to locate the failure instead of jumping ahead.
Inspect the components tied to the LIN circuit
If the external circuit is normal and the path calls for checking the LIN-connected components, start with the shutter grille connector, PCM connector A, alternator connector, 12 volt battery sensor connector, and DC-DC converter connector A disconnected. Then reconnect PCM connector A, the alternator, the 12 volt battery sensor, and the DC-DC converter one at a time while performing the LIN internal circuit inspection. With the shutter grille connector still disconnected and IG mode OFF, the normal condition is not shorted. If the short shows up when one item is reconnected, the problem is with the part that became shorted at that point. This check can be done early, but if it fails, you still need to continue through the individual inspection items to identify exactly which item failed.
Run the shutter grille diagnostic branch
For the shutter grille branch, the external circuit needs to be normal first. There is no direct component-only test for the shutter grille in this path, so the diagnosis is done by checking the related pieces around it. Run the confirmation procedure again and check whether the related shutter-grille LIN code is absent. If that check is normal, the path points to a problem with the shutter grille. If that check is abnormal, the path points back toward other related components.
Check the shutter grille circuit directly
Next, with the external circuit already normal, prepare for the shutter grille circuit inspection by disconnecting the alternator 1-pin connector, PCM connector A 50-pin, the 12 volt battery sensor 2-pin connector, and DC-DC converter connector A 3-pin. Follow the shutter grille circuit inspection, and with the alternator connector disconnected and IG mode OFF, inspect the shutter grille internal circuit. Normal is not shorted. If this inspection is abnormal, the problem is with the shutter grille. As with the earlier LIN check, this circuit inspection can be done before other checks, but if it fails, continue through the individual items so the failed item is actually isolated.
PCM decision and verification
Only after the other inspection items have shown normal does the remaining path identify the PCM as the cause. Keep that as the last call, not the first guess. For verification, use the confirmation check again: turn the vehicle to ON mode, wait 10 seconds, and confirm the target code does not return. The takeaway is simple: prove the power, ground, LIN circuit, connected components, and shutter grille path first, then make the PCM decision only after the rest of the path is clean. For more diagnostic training, visit stepdiagnostics.com.
Final check
P16E8 is best handled by proving the shared circuit and connected components before blaming the shutter grille or PCM.
For more guided automotive diagnostics, visit STEP Diagnostics.
