The P1398 trouble code is a manufacturer-specific powertrain code. Its exact definition depends entirely on the vehicle application, primarily indicating a crankshaft position sensor learning issue or a wheel speed sensor circuit fault.
Because it is manufacturer-specific, the exact application must be verified. The code identifies a detected condition, and testing is required to identify the root cause before replacing any components.
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Key Takeaways
- P1398 is a manufacturer-specific code with definitions varying significantly between automakers.
- On Chrysler, Dodge, and Jeep applications, it indicates the PCM is unable to learn the crankshaft position sensor signal for misfire diagnostics.
- On Honda, Acura, and some GM applications, it points to a wheel speed sensor or G-sensor circuit high voltage condition.
- Proper diagnosis requires verifying the exact factory definition and testing the relevant crankshaft or wheel speed sensor circuits.
- Repairs range from performing a crankshaft variation relearn procedure to replacing a confirmed failed sensor or repairing wiring.
P1398 Code Description and Implications
The P1398 code is a manufacturer-specific powertrain definition. Because it is not a generic SAE code, its exact meaning depends entirely on the vehicle application.
Chrysler, Dodge, and Jeep applications: P1398 indicates that the misfire adaptive numerator is at its limit. The powertrain control module is unable to learn the crankshaft position sensor’s signal variation, which disables the misfire monitor.
Honda, Acura, and General Motors applications: On these vehicles, P1398 indicates a wheel speed sensor or G-sensor circuit high voltage fault. The control module detects an out-of-range signal from the chassis or ABS sensor.
Common Causes of the P1398 Code
Electrical faults, sensor degradation, and software calibration issues are the primary triggers, though the specific causes vary by manufacturer.
For Chrysler, Dodge, and Jeep applications: The issue stems from a recent engine replacement or PCM replacement where the crankshaft variation relearn procedure was not performed, or a failing crankshaft position sensor.
For Honda, Acura, and GM applications: The fault is caused by a failed wheel speed sensor or G-sensor, damaged wiring harnesses, or a poor electrical connection at the sensor connector causing a short to voltage.
Symptoms Associated With P1398
When the control module detects a fault in these specific monitoring systems, it illuminates the Check Engine Light or ABS warning light.
Chrysler, Dodge, and Jeep applications: You may not notice any drivability symptoms. The primary effect is that the misfire monitor is disabled, which can cause the vehicle to fail an emissions inspection.
Honda, Acura, and GM applications: You may experience ABS or traction control system disablement. The stability control system may also illuminate a warning light on the dashboard.
Diagnosing the P1398 Trouble Code
Accurate diagnosis begins by confirming the exact factory definition for your specific vehicle make and model.
Chrysler, Dodge, and Jeep diagnosis: Connect a bidirectional scan tool capable of performing the crankshaft variation relearn procedure. If the relearn fails, inspect the crankshaft position sensor and its wiring for damage or excessive runout.
Honda, Acura, and GM diagnosis: Use a scan tool to monitor the live wheel speed sensor or G-sensor data. Verify the sensor reading and check the reference voltage, signal, and ground circuits to identify a short to voltage.
Repairing the P1398 Issue
Repairs must address the specific root cause identified during testing.
Crankshaft sensor and relearn repair: If the crankshaft variation relearn procedure was skipped after a battery disconnect or module replacement, perform the relearn. If the sensor fails electrical testing, replace the crankshaft position sensor.
Wheel speed sensor repair: If the wheel speed sensor or G-sensor signal is shorted to voltage and the wiring is intact, replace the confirmed failed sensor. Repair any chafed wires and clear the codes to verify the repair.
Cost Considerations for P1398 Repairs
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Performing a crankshaft variation relearn procedure is generally a straightforward service with minimal labor cost. Replacing a wheel speed sensor or crankshaft position sensor requires moderate parts and labor expenditure.
Prevention Strategies for Future Occurrences
Ensuring that a crankshaft variation relearn procedure is performed immediately after replacing the PCM, crankshaft position sensor, or engine assembly can prevent Chrysler, Dodge, and Jeep applications from setting this code.
Inspecting wheel speed sensor wiring near the wheel hubs for early signs of chafing, corrosion, or damage can help prevent circuit faults from developing on Honda, Acura, and GM vehicles.
Troubleshooting Tips and Best Practices
Do not immediately replace the crankshaft position sensor just because a P1398 code is present on a Chrysler or Jeep vehicle. A simple missed relearn procedure or a disconnected battery will produce the exact same fault reading.
Always verify the manufacturer-specific definition first. A code that means a missed crankshaft relearn on a Dodge means a wheel speed sensor circuit fault on a Honda or GM vehicle.
Check for Technical Service Bulletins for your specific vehicle. Manufacturers occasionally release updated relearn procedures or revised sensor part numbers to address chronic calibration and circuit issues.
More OBD-II Codes
| P1394 | P1395 | P1396 | P1388 |
| P1389 | P1390 | P1399 | P1404 |
| P1405 | P1406 | P1407 | P1408 |
| P0335 | P0500 | P0300 | P0340 |
| P0420 | P0430 | P0171 | P0174 |
| P1410 | P1415 | P1416 | P1418 |
Frequently Asked Questions
Is P1398 a generic or manufacturer-specific code?
No. P1398 is a manufacturer-specific powertrain code. It indicates a crankshaft relearn issue on Chrysler, and a wheel speed sensor circuit fault on Honda and GM.
Can I drive my car with a P1398 code?
Driving is generally possible. On Chrysler applications, the misfire monitor is disabled, which may cause an emissions test failure. On Honda or GM applications, ABS or traction control may be disabled.
Will disconnecting the battery clear the P1398 code?
Disconnecting the battery may temporarily erase the code, but it will not repair a failed sensor or damaged wiring. On Chrysler vehicles, a battery disconnect actually triggers the need for a crankshaft relearn.
Can a bad catalytic converter cause a P1398 code?
No. P1398 monitors the crankshaft position sensor learning or the wheel speed sensor circuit depending on the make. A catalytic converter efficiency issue triggers different codes, such as P0420.
Does P1398 always mean the sensor is bad?
No. The code identifies a detected circuit or calibration condition. On Chrysler vehicles, it is frequently caused by a missed relearn procedure. The sensor should only be replaced after testing confirms failure.
What Should You Do About the P1398 Code?
Confirm the exact factory definition for your vehicle, then follow the applicable manufacturer diagnostic procedure. Because P1398 is manufacturer-specific, the diagnostic path for a crankshaft variation relearn differs entirely from a wheel speed sensor circuit issue.
Inspect the relevant system and components, including the crankshaft position sensor, wheel speed sensors, and wiring circuits. Perform any required relearn procedures, or replace the relevant system components only after testing verifies the failure.
