What this code means
U0115 can indicate that the TCM is not receiving PCM signals through F-CAN.
What the vehicle may do
- The TCM may be unable to receive PCM signals through F-CAN.
- The TCM can store U0115 when those signals are not received.
Possible fault areas
- The PCM may not start normally.
- The PCM power/ground circuit may have a fault.
- The communication circuit, PCM, or TCM may be faulty.
Diagnostic path
What U0115 means
Perform the following inspections based on the DTC stored in each unit. DTC Inspection Items Work Items PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection PCM: U0101 External Circuit (PCM~TCM) PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection PCM: U0101 Control Unit (PCM~TCM) PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection TCM: U0115 External Circuit (TCM~PCM) PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection TCM: U0115 Control Unit (TCM~PCM) Electric Brake Booster: VF-CAN A_H, VF-CAN A_L, VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN U0122-00, External Circuit B_L Open Wire Inspection (Electric Brake Booster~VSA Modulator-Control U0128-00 Unit) Electric Brake Booster: VF-CAN A_H, VF-CAN A_L, VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN U0122-00, Control Unit B_L Open Wire Inspection (Electric Brake Booster~VSA Modulator-Control U0128-00 Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection Electric Brake Booster: U0151-00 External Circuit (Electric Brake Booster~SRS Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection Electric Brake Booster: U0151-00 Control Unit (Electric Brake Booster~SRS Unit) VSA Modulator-Control Unit: U0123- VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection External Circuit 00 (VSA Modulator-Control Unit~SRS Unit) VSA Modulator-Control Unit: U0123- VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection Control Unit 00 (VSA Modulator-Control Unit~SRS Unit) VSA Modulator-Control Unit: U0126- VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection External Circuit 00 (VSA Modulator-Control Unit~EPS Control Unit) VSA Modulator-Control Unit: U0126- VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection Control Unit 00 (VSA Modulator-Control Unit~EPS Control Unit) VF-CAN A_H, VF-CAN A_L, VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN VSA Modulator-Control Unit: U0129- External Circuit B_L Open Wire Inspection (VSA Modulator-Control Unit~Electric Brake 00 Booster) VF-CAN A_H, VF-CAN A_L, VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN VSA Modulator-Control Unit: U0129- Control Unit B_L Open Wire Inspection (VSA Modulator-Control Unit~Electric Brake 00 Booster) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection EPS Control Unit: U0122-00 External Circuit (EPS Control Unit~VSA Modulator-Control Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection EPS Control Unit: U0122-00 Control Unit (EPS Control Unit~VSA Modulator-Control Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L, VF-CAN C_H, VF- EPS Control Unit: U0151-00 External Circuit CAN C_L Open Wire Inspection (EPS Control Unit~SRS Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L, VF-CAN C_H, VF- EPS Control Unit: U0151-00 Control Unit CAN C_L Open Wire Inspection (EPS Control Unit~SRS Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection SRS Unit: U0122-00 External Circuit (SRS Unit~VSA Modulator-Control Unit) VF-CAN L_H/VF-CAN B_H, VF-CAN L_L/VF-CAN B_L Open Wire Inspection SRS Unit: U0122-00 Control Unit (SRS Unit~VSA Modulator-Control Unit)
On this 2025 Honda Accord 1.5, U0115 means PF-CAN C Malfunction (TCM - PCM). The TCM stores this code when it cannot receive PCM signals through F-CAN. This diagnostic path covers an F-CAN lost communication fault on a circuit not connected to the CAN gateway. A PCM startup problem or power/ground fault can also lead to this code. Here is what this code tells us. The TCM may be unable to receive PCM signals through F-CAN. The TCM can store U0115 when those signals are not received. Here are the main areas to check. The PCM may not start normally. The PCM power/ground circuit may have a fault. The communication circuit, PCM, or TCM may be faulty.
Before the circuit checks
Troubleshoot any DTCs listed or indicated systems below first. － Network Communications \[CAN gateway\]: Go to the indicated DTC's troubleshooting
Before you troubleshoot, review How to Troubleshoot. For U0115, check the PCM power/ground circuit first, before troubleshooting. If the failure happens intermittently or is difficult to reproduce, review How to Troubleshoot (Handling Intermittent and Low Reproducibility Failures). Check the transmitting control unit's power/ground circuit based on the stored DTC. If Network Communications \[CAN gateway\] codes are present, troubleshoot those indicated codes first. Choose the inspections based on the DTC stored in each unit. For U0115 stored in the TCM, the external-circuit and control-unit entries both identify the PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection (TCM~PCM).
The TCM stores the code because PCM signals are not being received; that does not by itself identify the TCM as faulty. A PCM startup problem or PCM power/ground fault can also produce this code. This is why the PCM power/ground check comes before the U0115 communication troubleshooting.
Shared confirmation routine
The shared confirmation routine is defined separately from the circuit inspection. Its action is to turn the vehicle to the ON mode. For the details, check the confirmation procedure for the DTC being checked.
Prepare the open-wire inspection
Here is the separate physical test routine: PF-CAN A_H, PF-CAN A_L, PF-CAN C_H, PF-CAN C_L Open Wire Inspection (TCM~PCM). Before you disconnect the TCM connector and the PCM connector, jump the SCS line with the diagnostic scanner (HDS). Wait more than 1 minute. Then disconnect TCM connector (50P) and PCM connector A (72P). Check the four circuits at the terminal pairs that follow, using the stated conditions for each check.
PF-CAN A_H
With IG Mode OFF and both connectors disconnected, check PF-CAN A_H for continuity. Place one probe on TCM connector (50P) female terminal 3. Place the other probe on PCM connector A (72P) female terminal 69. The normal reading is less than 1 ohm.
PF-CAN A_L
With IG Mode OFF and both connectors disconnected, check PF-CAN A_L for continuity. Place one probe on TCM connector (50P) female terminal 11. Place the other probe on PCM connector A (72P) female terminal 55. The normal reading is less than 1 ohm.
PF-CAN C_H
With IG Mode OFF and both connectors disconnected, check PF-CAN C_H for continuity. Place one probe on TCM connector (50P) female terminal 4. Place the other probe on PCM connector A (72P) female terminal 70. The normal reading is less than 1 ohm.
PF-CAN C_L
With IG Mode OFF and both connectors disconnected, check PF-CAN C_L for continuity. Place one probe on TCM connector (50P) female terminal 12. Place the other probe on PCM connector A (72P) female terminal 56. The normal reading is less than 1 ohm.
Although the code description names PF-CAN C, the TCM's U0115 entry calls for the complete four-circuit open-wire inspection, including PF-CAN A_H and PF-CAN A_L. A result from only the C circuits therefore does not cover the full inspection used for the circuit-versus-control-unit decision.
What the circuit results mean
If the inspection results are abnormal, the problem is in the circuit. If the results are normal, the problem is with the PCM. If the failure is reproduced using a known-good PCM, the TCM must be faulty.
The TCM diagnosis has an additional condition: the failure must be reproduced using a known-good PCM. Normal circuit results alone lead to the PCM branch, not directly to a TCM diagnosis. Reproducing the failure with the known-good PCM is what distinguishes the stated TCM conclusion from the initial PCM conclusion.
U0115-specific diagnostic path
The U0115-specific troubleshooting has its own prerequisite. Before this troubleshooting, check the power/ground circuit of the PCM first. Then use the troubleshooting for F-CAN Lost Communication (CAN BUS without Connection to CAN Gateway).
U0115 confirmation routine
The U0115 confirmation routine is defined separately. Its action is to turn the vehicle to the ON mode and wait for at least 2 seconds.
Scanner function reference
The scanner function listing includes AT ＞ Data List.
Final check
PCM startup, PCM power/ground, the communication circuit, and the control units can be relevant to U0115.
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