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 P2237 (2017 2018 2019 2020 2021)
DTC P2237 : A/F Sensor (Sensor 1) AFS Circuit High Voltage
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC |
|---|---|---|
| P2237 A/F Sensor (Sensor 1) AFS Circuit High Voltage |
DTC (PGM-FI)
- Problem verification
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
-3. Start the engine, and wait for 1 minute.
-4. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P2237 A/F Sensor (Sensor 1) AFS Circuit High Voltage Is DTC P2237 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), 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 .
- Open 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 PCM connector B (51P) No. 43 Test point 2 A/F sensor (Sensor 1) 4P connector No. 1 Is there continuity?
YES
The AFC1 wire is OK. Go to step 3.
NO
Repair an open in the AFC1 wire between the PCM (B43) and the A/F sensor (Sensor 1).
- Open wire check (AFV1 line)
-1. 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 PCM connector B (51P) No. 42 Test point 2 A/F sensor (Sensor 1) 4P connector No. 2 Is there continuity?
YES
The AFV1 wire is OK. Go to step 4.
NO
Repair an open in the AFV1 wire between the PCM (B42) and the A/F sensor (Sensor 1).
- A/F sensor (Sensor 1) check (substitution)
-1. Substitute a known-good A/F sensor (Sensor 1) .
-2. Reconnect all connectors.
-3. Turn the vehicle to the ON mode.
-4. Reset the PCM with the HDS .
Reset PCM
-5. Do the PCM idle learn procedure .
-6. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC P2237 A/F Sensor (Sensor 1) AFS Circuit High Voltage Is DTC P2237 indicated?
YES
The A/F sensor (Sensor 1) is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P2237 goes away and the PCM was updated, troubleshooting is complete. If DTC P2237 goes away and the PCM was substituted, replace the original PCM .
NO
NO RELATED
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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.