Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P2238
DTC P2238 : A/F Sensor (Sensor 1) AFS+ Circuit Low Voltage
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| P2238 A/F Sensor (Sensor 1) AFS+ Circuit Low Voltage |
DTC (PGM-FI)
- Problem verification
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
-3. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC Freeze Frame P2238 A/F Sensor (Sensor 1) AFS+ Circuit Low Voltage Is DTC P2238 indicated?
YES
The failure is duplicated. Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot .
- Shorted wire check (AFC1 line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS.
-3. Disconnect the following connectors.
A/F sensor (Sensor 1) 4P connector PCM connector B (51P) -4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode A/F sensor (Sensor 1) 4P connector: disconnected PCM connector B (51P): disconnected Test point 1 A/F sensor (Sensor 1) 4P connector No. 1 Test point 2 Body ground Is there continuity?
YES
Repair a short in the AFC1 wire between the PCM (B43) and the A/F sensor (Sensor 1).
NO
The AFC1 wire is OK. Go to step 3.
- PCM internal circuit check
-1. Reconnect the PCM connector B (51P).
-2. Exit the SCS mode with the HDS.
-3. Turn the vehicle to the ON mode.
-4. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode A/F sensor (Sensor 1) 4P connector: disconnected Test point 1 A/F sensor (Sensor 1) 4P connector No. 1 Test point 2 Body ground Is there about 0.2 V or less?
YES
Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P2238 goes away and the PCM was updated, troubleshooting is complete. If DTC P2238 goes away and the PCM was substituted, replace the original PCM .
NO
The PCM internal circuit is OK. Replace the A/F sensor (Sensor 1) .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.