What this code means
P2623 may indicate that the ECM/PCM is seeing a problem with the high pressure fuel pump spill valve control circuit.
What the vehicle may do
- The vehicle may crank longer than normal or may not start.
- The engine may run poorly or feel down on power.
- The malfunction indicator may come on.
Possible fault areas
- Possible areas can include the high pressure fuel pump spill valve circuit.
- Possible areas can include wiring, terminals, or connector fit at the pump and PCM.
- Possible areas can include relay-controlled power feeds and fuse-protected supply circuits.
- Possible areas can include PCM command or control-side concerns.
Diagnostic path
Opening context
On this 2010 to 2017 Honda Accord with the 2.4 gas engine, P2623 points us toward a possible control problem for the high pressure fuel pump spill valve. The car may crank longer than normal, may not start, may run poorly, or may set the light with fuel control complaints. Broadly, we’re thinking about the pump spill valve circuit, the power and relay feed side, connector condition, wiring between the pump and the PCM, and the PCM command side. Before getting deep into pin testing, start with the basic system checks and follow a structured diagnostic approach so you are not chasing a wiring code with a weak foundation.
Confirm the fault before testing
First, verify the problem. Turn the ignition switch to ON (II), or use the engine start/stop button to select ON mode. Clear the DTC with the HDS, then start the engine. If the engine does not start, crank it for 20 seconds. After that, check pending and confirmed DTCs with the HDS. The first decision is whether P2623 is setting together with injector circuit codes. If it is, the failure is duplicated and the path starts with the injector relay and feed circuits. If it is not setting that way, there is an unclear split in the path, so do not guess. Pause and confirm what the car is actually doing: if the P2623 failure is duplicated, continue with the high pressure pump circuit checks; if it is not duplicated, treat it as intermittent, inspect for poor connections or loose terminals at the high pressure fuel pump spill valve and the PCM, and reproduce the captured conditions if that data is available.
Check the relay and the power feeds
If P2623 is duplicated with the injector circuit group, turn the ignition switch to LOCK (0), or select OFF mode, remove the injector relay from under-dash relay holder C at the upper side of the driver’s kick panel, and test the relay. If the relay fails, replace the injector relay. If the relay is OK, leave it disconnected and turn the ignition back to ON (II), or ON mode. Check the FI MAIN RLY OUT circuit for battery voltage between under-dash relay holder C 8P connector No. 5, BRN, and body ground. If battery voltage is missing, repair the open between PGM-FI main relay 1 and the injector relay. If that feed is good, check the +B INJ circuit for battery voltage between under-dash relay holder C 8P connector No. 1, RED, and body ground. If battery voltage is present, move on to the relay control side. If it is not present, check fuse No. A10 (20 A) in the under-hood fuse/relay box. If the fuse is OK, repair the open in the +B INJ wire between that fuse and the injector relay. If the fuse is blown, repair the short in that same +B INJ wire and replace fuse No. A10 (20 A).
Check relay control and relay output to the PCM
Next, check whether the PCM-side relay control is being pulled the way it should. With the injector relay still disconnected, turn the ignition to ON (II), or ON mode, and measure voltage momentarily between under-dash relay holder C 8P connector No. 5, BRN, and No. 6, LT GRN, on the INJ RLY CL- circuit. If battery voltage appears momentarily, go to the relay output check. If it does not, turn the ignition OFF, install the injector relay, jump the SCS line with the HDS, disconnect PCM connector A (51P), turn the ignition back ON, and check for battery voltage at PCM connector A (51P) No. 15, LT GRN, to body ground. If voltage is missing there, repair the open in the INJ RLY CL- wire between the injector relay and PCM terminal A15. If voltage is present, the INJ RLY CL- wire is OK; at that point, pause and check for current OEM direction tied to the DTCs or symptoms, or substitute a known-good PCM. For the relay output check, turn the ignition OFF, connect under-dash relay holder C 8P connector No. 1, RED, to No. 2, PUR, with a jumper wire, jump the SCS line with the HDS, disconnect PCM connector A (51P), turn the ignition ON, and check the INJ RLY OUT circuit for battery voltage at PCM connector A (51P) No. 6, PUR, and No. 7, PUR, to body ground. If both outputs have battery voltage, continue to the high pressure pump circuit checks. If not, repair the open in the INJ RLY OUT wire between the injector relay and PCM terminals A6 and A7.
Check the high pressure pump circuit for opens
Now move to the HPUMP H and HPUMP L circuits. Turn the ignition to LOCK (0), or OFF mode, install the injector relay, jump the SCS line with the HDS, disconnect PCM connector C (51P), and check continuity between PCM connector C (51P) No. 13, WHT, and No. 14, BLK. If there is no continuity, go straight into the short-to-power checks. If there is continuity, the two pump wires are not open as a pair, so isolate each leg. Disconnect the high pressure fuel pump 2P connector and check continuity on HPUMP H between high pressure fuel pump 2P connector No. 1, WHT, and PCM connector C (51P) No. 13, WHT. If it is open, repair the HPUMP H wire between the high pressure fuel pump and PCM terminal C13. If HPUMP H has continuity, check HPUMP L between high pressure fuel pump 2P connector No. 2, BLK, and PCM connector C (51P) No. 14, BLK. If it is open, repair the HPUMP L wire between the high pressure fuel pump and PCM terminal C14. If HPUMP L is OK too, pause and check for current OEM direction tied to the DTCs or symptoms, or substitute a known-good PCM.
Check the pump wires for shorts
If the HPUMP H and HPUMP L circuit check sent you toward short testing, keep PCM connector A (51P), PCM connector C (51P), and the high pressure fuel pump 2P connector disconnected. Turn the ignition to ON (II), or ON mode, and check HPUMP H for unwanted voltage between PCM connector C (51P) No. 13, WHT, and body ground. If voltage is present, repair the short to power in the HPUMP H wire between the high pressure fuel pump and PCM terminal C13. If not, check HPUMP L the same way between PCM connector C (51P) No. 14, BLK, and body ground. If voltage is present, repair the short to power in the HPUMP L wire between the high pressure fuel pump and PCM terminal C14. If neither wire is shorted to power, turn the ignition OFF and check for continuity to ground. On HPUMP H, check between PCM connector C (51P) No. 13, WHT, and body ground. If there is continuity, repair the short in the HPUMP H wire between the pump and PCM terminal C13. If there is no continuity, HPUMP H is OK. Then check HPUMP L between PCM connector C (51P) No. 14, BLK, and body ground. If there is continuity, repair the short in the HPUMP L wire between the pump and PCM terminal C14. If there is no continuity, HPUMP L is OK; at that point, pause and check for current OEM direction tied to the DTCs or symptoms, or substitute a known-good PCM.
Verification and takeaway
After any repair, keep verification separate from the circuit testing. Clear the code with the HDS, run the engine if it starts, or use the same no-start crank routine if it does not, then recheck pending and confirmed DTCs. The takeaway on P2623 is to prove whether the fault is part of the relay and injector power feed side, or isolated to the high pressure pump spill valve wiring between the pump and PCM, before making a call on any module-level direction. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code often needs a circuit-first diagnosis so the relay feed side and the pump control wiring are proven before broader conclusions are made.
For more guided automotive diagnostics, visit STEP Diagnostics.
