# HL7812 GNSS Not Working – GNSSSTART Resets, CME Errors, FIX NOT AVAILABLE **URL:** \ **Category:** XS Series (GNSS)\ **Created:** [December 15, 2025, 6:35am UTC](https://forum.sierrawireless.com/t/hl7812-gnss-not-working-gnssstart-resets-cme-errors-fix-not-available/35668 "2025-12-15T06:35:09Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![vagesh.p](https://avatars.discourse-cdn.com/v4/letter/v/c77e96/32.png) [@vagesh.p](https://forum.sierrawireless.com/u/vagesh.p)\ **Post date:** [December 15, 2025, 6:35am UTC](https://forum.sierrawireless.com/t/hl7812-gnss-not-working-gnssstart-resets-cme-errors-fix-not-available/35668/1 "2025-12-15T06:35:09Z")
I am working with the **HL7812 module** and facing issues enabling and using **GNSS**. Despite following the standard AT command sequence, GNSS does not provide a fix and several GNSS-related commands return errors. Below are the complete module details and command logs for your reference. **Module Information (ATI9):** HL7812.5.4.12.2-23.01.0.FreeRTOS.rc2 HL78xx.5.4.12.2.RK\_03\_02\_00\_22\_24731\_001.20230330 Build Date: 2023/03/30 08:42:08 IMEI-SV: 3511444414172812 Legato RTOS: 23.01.0.FreeRTOS.rc2 UBOOT: 01.03 Apps: RKAPP\_03\_02\_00\_22\_24651\_001 MAC: ALT1250\_03\_02\_00\_22\_24731\_2G PHY: 12.50.314023 PMP: 315260 AISE: ISE2APP\_00\_00\_00\_09 SBUB: 1 SBFW: 1 RBUB: 0 RBFW: 0 MCU-Disable: 1 **GNSS Test Logs:** AT+CFUN? +CFUN: 1 OK AT+GNSSSTART=1 OK +GNSSEV: 0,1 +GNSSEV: 1,0 AT+GNSSSTART? +GNSSSTART: 0 OK AT+GNSSNMEA? +CME ERROR: 60 AT+GNSSLOC? +GNSSLOC: FIX NOT AVAILABLE OK **Additional Test with CFUN Toggle:** AT+CFUN=4 OK AT+GNSSSTART=1 OK +GNSSEV: 1,1 AT+CFUN=1 OK AT+GNSSNMEA=1,1,0,0x49 +CME ERROR: 3 AT+GNSSLOC? +GNSSLOC: FIX NOT AVAILABLE OK **Sleep Configuration:** AT+KSLEEP? +KSLEEP: 2 OK AT+KSLEEP=0 +CME ERROR: 3 **Issues Observed** : - `AT+GNSSSTART=1` does not remain enabled (`GNSSSTART?` returns `0`) - GNSS NMEA and configuration commands return CME ERROR 3 / 60 - GNSS never reports a valid fix (FIX NOT AVAILABLE) - Unable to modify KSLEEP settings - GNSS events indicate inconsistent states (+GNSSEV: 1,0 / 1,1) **Questions:** 1. Does firmware HL7812.5.4.12.2-23.01.0.FreeRTOS.rc2 support GNSS fully? 2. What is the root cause/source of GNSS automatically disabling (GNSSSTART` returning 0)? 3. Are CME ERROR 3 and 60 expected for GNSS commands under this firmware? 4. Does KSLEEP = 2 or MCU-Disable = 1 prevent GNSS operation? 5. Is there a known limitation, missing configuration, or firmware bug in HL7812.5.4.12.2-23.01.0.FreeRTOS.rc2 affecting GNSS? 6. What is the correct sequence to reliably enable GNSS and obtain a fix on this platform? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [December 15, 2025, 7:08am UTC](https://forum.sierrawireless.com/t/hl7812-gnss-not-working-gnssstart-resets-cme-errors-fix-not-available/35668/2 "2025-12-15T07:08:17Z")
i saw other user can make the +GNSSNMEA work in newer firmware: > [@Clarification on Proprietary NMEA Sentence \[HL7812.5.5.14.0\]](https://forum.sierrawireless.com/t/clarification-on-proprietary-nmea-sentence-hl7812-5-5-14-0/34478/3): > > No, its from UART1 I am working on a custom board, but I think you should be able to generate it if it is a modem sw issue. These are all the AT commands to start searching and get GNSS data: +WDSI: 0 +CEREG: 2 +CREG: 2 +KSUP: 0 [00:00:09.664,000] \ modem\_hl7812: send\_at\_cmd: OUT: [AT+KSRAT?] +KSRAT: 1 OK [00:00:09.668,000] \ modem\_hl7812: send\_at\_cmd: OUT: [AT+CEREG=0] OK [00:00:10.060,000] \ modem\_hl7812: send\_at\_cmd: OUT: [AT+CREG=0] OK [00:00:10.522,000] \ modem\_hl7812:… BTW, GNSSSTART return zero means the following: ![image](https://us1.discourse-cdn.com/flex025/uploads/sierrawireless/original/2X/c/c58c3110436db840c850299c0fa4a12e1a1dfcc9.png) ---
**Author:** ![vagesh.p](https://avatars.discourse-cdn.com/v4/letter/v/c77e96/32.png) [@vagesh.p](https://forum.sierrawireless.com/u/vagesh.p)\ **Post date:** [December 16, 2025, 5:13am UTC](https://forum.sierrawireless.com/t/hl7812-gnss-not-working-gnssstart-resets-cme-errors-fix-not-available/35668/3 "2025-12-16T05:13:55Z")
> [@Clarification on Proprietary NMEA Sentence \[HL7812.5.5.14.0\]](https://forum.sierrawireless.com/t/clarification-on-proprietary-nmea-sentence-hl7812-5-5-14-0/34478/3): > > `AT+GNSSNMEA=4` I have some Doubt / Question - Is **GNSS disabled or restricted when CS (2G/3G) services are enabled** on the HL78xx? - Is it mandatory to **disable CS (2G/3G)** for GNSS to work correctly? - What is the **correct configuration or AT command sequence** to allow GNSS operation when CS is enabled? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [December 16, 2025, 5:17am UTC](https://forum.sierrawireless.com/t/hl7812-gnss-not-working-gnssstart-resets-cme-errors-fix-not-available/35668/4 "2025-12-16T05:17:02Z")
According to specification, i don’t think the HL78 module is supporting 3G… ![image](https://us1.discourse-cdn.com/flex025/uploads/sierrawireless/original/2X/b/bbcca648421e2c5d0c8d6af5dc91a609d76b5ab8.png)