Chevrolet P1B03
Labor Operation Description Labor Time 5430940 Engine Wiring Harness Replacement Use Published Labor Operation Time Version 4
Quick answer
For the Chevrolet Bolt EV and Bolt EUV applications listed below, DTC P1B03 is addressed in GM bulletin 19-NA-220. The verified bulletin evidence states that terminals do not need visible damage to set P1B03 and identifies Engine Wiring Harness Replacement as the applicable warranty labor operation when that repair is performed.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
Watch Videos
Relevant videos play here without leaving this diagnostic page.
No sufficiently relevant embeddable video has been accepted for this diagnostic yet.
Videos are supporting material and never override OEM or regulator evidence.
1. What does P1B03 mean?
For the Chevrolet Bolt EV and Bolt EUV applications listed below, DTC P1B03 is addressed in GM bulletin 19-NA-220. The verified bulletin evidence states that terminals do not need visible damage to set P1B03 and identifies Engine Wiring Harness Replacement as the applicable warranty labor operation when that repair is performed.
2. Technical explanation
The supplied verified evidence does not establish a standard diagnostic-text definition for P1B03. Its canonical title is a labor-operation description, not a fault definition. In GM bulletin 19-NA-220, Chevrolet identifies connector seating/alignment and terminal condition as relevant inspection subjects. The bulletin states that terminals do not need to have visible damage to set DTC P1B03. It also directs use of the VIN and GM Electronic Parts Catalog to determine the correct engine wiring harness if replacement is required.
3. What system is affected?
Engine wiring harness and related connectors/terminals, as described by GM bulletin 19-NA-220.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
- Not yet established by verified evidence.
6. Possible causes
- A connector may not be fully seated, based on the connector-seating instruction in GM bulletin 19-NA-220.
- Improper alignment of the X2 connector is illustrated in GM bulletin 19-NA-220.
- Terminal condition may be relevant; GM states terminals do not need visible damage to set P1B03.
- No further cause is established by the supplied verified evidence.
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Arrange diagnosis by a Chevrolet/GM-qualified service provider.
- Provide the technician with DTC P1B03 and reference GM bulletin 19-NA-220.
- Do not attempt high-voltage or wiring-harness repair yourself.
10. Step-by-step troubleshooting
- GM bulletin 19-NA-220 instructs attention to connector installation: connectors should be fully seated and should not be installed at an angle.
- The bulletin includes examples of proper and improper X2 connector alignment.
- A qualified technician can inspect relevant connector and terminal condition. The evidence notes that the absence of visible terminal damage does not rule out P1B03.
- If engine wiring harness replacement is needed, GM directs use of the VIN and GM Electronic Parts Catalog to identify the correct harness.
11. When to contact service
Service is recommended because the verified GM bulletin provides a connector/terminal and engine-wiring-harness repair path for P1B03, but it does not establish whether driving or charging is safe.
12. What the service center may check
- Check that applicable connectors are fully seated.
- Check that connectors were not installed at an angle.
- Inspect relevant terminals; visible terminal damage is not required for P1B03 to set.
- Use the VIN and GM Electronic Parts Catalog to determine the appropriate engine wiring harness if replacement is required.
13. Possible repair or resolution
- GM bulletin 19-NA-220 lists Engine Wiring Harness Replacement when that repair is required.
- The 2021 version of the bulletin lists warranty labor operation 5430940, Engine Wiring Harness Replacement, using published labor operation time, Version 4.
- The 2023 version of the bulletin lists the same labor operation using Version 6.
- Whether harness replacement resolves a particular vehicle's P1B03 is not established by the supplied evidence.
14. Affected vehicles
- Chevrolet Bolt EUV · 2017–2023 · US
- Chevrolet Bolt EV · 2017–2023 · US
- Chevrolet Bolt EV · 2017–2021 · US
15. Related TSBs / service bulletins
- GM/Chevrolet bulletin 19-NA-220, published March 8, 2021: https://static.nhtsa.gov/odi/tsbs/2021/MC-10191195-9999.pdf
- GM/Chevrolet bulletin 19-NA-220, published February 13, 2023: https://static.nhtsa.gov/odi/tsbs/2023/MC-10232147-0001.pdf
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Official NHTSA-hosted manufacturer communications for GM bulletin 19-NA-220 are provided in the TSB/service-bulletins field.
19. Frequently asked questions
What does P1B03 mean on the Chevrolet Bolt?
The supplied verified evidence does not establish a standard fault definition for P1B03. GM bulletin 19-NA-220 discusses P1B03 in connection with connector seating, X2 connector alignment, terminal condition, and possible engine wiring harness replacement.
Can terminals look normal and still set P1B03?
Yes. GM bulletin 19-NA-220 states that terminals do not need to have visible damage to set DTC P1B03.
Does P1B03 require engine wiring harness replacement?
Not necessarily. The bulletin provides engine wiring harness replacement as a repair operation when required, but the supplied evidence does not establish that every P1B03 requires harness replacement.
Which vehicles are covered by the supplied applicability data?
Chevrolet Bolt EV model years 2017–2023 and Chevrolet Bolt EUV model years 2017–2023 in the US. The supplied data also contains a separate Bolt EV 2017–2021 entry.