B1632 – DR Knee ABG Squib Open

The Mitsubishi fault code B1632 – Driver Knee Airbag Squib Open Circuit is a manufacturer-specific diagnostic trouble code stored by the SRS (Supplemental Restraint System) airbag ECU on Mitsubishi vehicles. It indicates that the airbag control module has detected an open circuit — a complete break in the electrical path — in the squib (initiator) circuit of the driver’s knee airbag inflator. With this fault present, the driver knee airbag cannot be guaranteed to deploy in a collision, and the SRS warning light will be continuously illuminated.

What Does B1632 Mean on a Mitsubishi?

The squib is the pyrotechnic initiator element inside an airbag inflator. The SRS ECU continuously supplies a small monitoring current through each squib circuit and checks that the measured resistance remains within a calibrated window — typically a very narrow range specific to the squib type. B1632 is stored when the SRS ECU measures infinite or near-infinite resistance on the driver knee airbag squib circuit, indicating that the circuit is broken somewhere between the SRS ECU and the inflator. This prevents the firing current from reaching the squib in a deployment event, rendering the knee airbag inoperative.

Symptoms of B1632

B1632 typically presents with the following indicators:

• SRS warning light continuously illuminated on the instrument cluster
• B1632 stored in the SRS/airbag ECU when scanned with MUT-III or compatible scanner
• Driver knee airbag inoperative — will not deploy in a collision event
• Other SRS functions (front airbags, side curtains, seatbelt pretensioners) may remain operational but the entire SRS system is flagged as degraded
• No driveability symptoms — B1632 is an SRS electrical fault only

Common Causes of B1632

• Failed or damaged knee airbag inflator squib — internal open circuit within the inflator itself; the most common cause on higher-mileage vehicles
• Corroded or damaged clock spring / spiral cable connector — if the knee airbag squib wiring passes through a rotary connector, corrosion or damage here will break the circuit
• Broken, chafed, or pinched squib wiring harness — wiring routed behind or beneath the dashboard is vulnerable to damage during previous repair work or rodent activity
• Corroded or unseated SRS harness connector at the knee airbag module — the yellow SRS connectors are shorting bar–equipped and must be fully seated to maintain circuit continuity
• Corroded or loose SRS ECU connector pin — open at the ECU end rather than at the inflator
• Previous collision damage or airbag deployment — a previously deployed knee airbag inflator will have a severed squib circuit and must be replaced
• Improper prior repair — incorrect reconnection or splicing of SRS harness during dashboard or steering column work

Common Misdiagnoses

• SRS ECU replaced unnecessarily: The ECU is rarely the cause of B1632. The open circuit is almost always in the wiring, connector, or inflator itself. Always trace the circuit from the inflator inward before condemning the ECU.
• Squib resistance tested with a standard multimeter: Using an unregulated multimeter across squib terminals is a serious safety hazard — even the small current from a DMM can trigger deployment. This is not a standard continuity test circuit. Only approved SRS resistance simulators and break-out boxes should be used.
• Code cleared without identifying the root cause: B1632 will return immediately if the open circuit is not repaired. Clearing the code is only valid as a post-repair confirmation step.
• Assuming the knee airbag was deployed in a previous collision: Always visually confirm whether the knee airbag module has physically deployed before condemning it — an undeployed module with a failed squib is a different repair to a post-collision replacement.

Affected Mitsubishi Vehicles

Model	Generation	Notes	Years
Outlander PHEV	GG/GF (1st Gen)	Driver knee airbag fitted as standard on most markets	2013–2021
Outlander PHEV	GN (2nd Gen)	Revised SRS architecture; same B1632 definition	2022–present
Outlander (non-PHEV)	GF/GG/ZJ/ZK/ZL	Knee airbag fitment market-dependent — verify before diagnosing	2007–present
Eclipse Cross	GK/GL	Shares SRS module architecture with Outlander	2017–present
ASX / RVR	GA/XD	Later models with knee airbag option	2016–present
Galant Fortis / Lancer	CY/CZ	Some market-specific trims include driver knee airbag	2007–2017

Tools & Equipment Required

Tool	Purpose	Notes
Mitsubishi MUT-III / MUT-IV	SRS scan, live data, code clear	Required to confirm B1632 and clear after repair
SRS break-out box / squib resistance simulator	Safe circuit resistance measurement	Never use a standard DMM directly across squib terminals
Digital multimeter (DMM)	Wiring continuity and voltage checks away from squib circuit	Only for harness segments with SRS connectors fully disconnected and shorting bars engaged
Wiring diagram (OEM)	Identify squib circuit routing for B1632	Mitchell1 DIY or Mitsubishi FAST-II
Electrical contact cleaner & dielectric grease	SRS connector cleaning	Clean all yellow SRS connectors before reconnecting
Trim removal tools	Dashboard and lower fascia access	Plastic pry tools to avoid marking surfaces

Step-by-Step Diagnosis

• 1
  Disable the SRS System Before Any WorkSwitch off the ignition, remove the SRS fuse (or disconnect the battery negative terminal), and wait a minimum of 60 seconds before touching any SRS component or connector. This allows the SRS capacitor to fully discharge and eliminates any risk of accidental deployment.
• 2
  Confirm B1632 with a Full SRS ScanReconnect power and use MUT-III or equivalent to read all SRS fault codes. Note whether B1632 is current or historical, and whether any other SRS codes are present that may indicate a related wiring or module fault.
• 3
  Visually Inspect the Knee Airbag ModuleWith SRS disabled, remove the lower dashboard trim to access the knee airbag module. Inspect whether the airbag has physically deployed. Inspect the yellow SRS connector for corrosion, bent pins, or incomplete seating. Ensure the shorting bar is functioning correctly in the connector body.
• 4
  Check Squib Circuit Resistance Using a Break-Out BoxConnect an SRS-approved break-out box or squib resistance simulator at the SRS ECU harness connector. Measure resistance on the knee airbag squib circuit. An open circuit reading (OL / infinite) with the inflator connected confirms either a wiring open or a failed inflator. Disconnect the inflator connector and re-measure — if the open moves to the harness side, the wiring is at fault; if the inflator connector now reads correctly, the inflator squib has failed internally.
• 5
  Trace the Squib Wiring HarnessIf the open circuit is in the wiring, trace the squib harness from the knee airbag module back to the SRS ECU connector, checking all intermediate connectors, routing clips, and areas where the harness may have been pinched, chafed, or incorrectly repaired during previous dashboard work.
• 6
  Check the SRS ECU Connector PinsIf no fault is found in the harness or inflator, inspect the SRS ECU harness connector pins for the knee airbag squib circuit. Spread or corroded pins at the ECU end can cause an intermittent or permanent open that is missed during a simple visual inspection of the module-side connector.

Scanner Readout Explained

====================================================
  MITSUBISHI MUT-III SE — DIAGNOSTIC REPORT
====================================================
  Vehicle:     2019 Outlander PHEV (GG3W)
  Date:        2025-03-27  11:22:38
====================================================
MODULE: SRS / AIRBAG ECU
----------------------------------------------------
  B1632  Driver Knee Airbag Squib — Open Circuit
         Status:       Confirmed / Current
         Freeze Frame:
           Squib Circuit Resistance:   OL (open, no continuity)
           Expected Resistance Range:  2.0–3.0 Ω (typical squib spec)
           SRS Warning Lamp:          ON
====================================================
  LIVE DATA (SRS System Status)
====================================================
  Driver Front Airbag Squib:     OK
  Passenger Front Airbag Squib:  OK
  Driver Knee Airbag Squib:      OPEN CIRCUIT — FAULT ACTIVE
  Side Curtain L Squib:          OK
  Side Curtain R Squib:          OK
  Seatbelt Pretensioner L:       OK
  Seatbelt Pretensioner R:       OK
====================================================
  NOTE: SRS system flagged as degraded.
  Knee airbag deployment not guaranteed in collision.
====================================================

Step-by-Step Repair Guide

Repair Path A: Knee Airbag Inflator Replacement

• 1
  Disable the SRS SystemRemove the SRS fuse and disconnect the battery negative terminal. Wait a minimum of 60 seconds before proceeding to allow the backup capacitor to discharge fully.
• 2
  Remove the Lower Dashboard TrimUsing plastic trim tools, carefully remove the lower dashboard fascia to gain access to the knee airbag module mounting. Refer to the workshop manual for the specific trim removal sequence for your model year — fastener locations vary across generations.
• 3
  Disconnect the Knee Airbag Squib ConnectorLocate the yellow SRS connector at the knee airbag module. Press the secondary lock release and disconnect the connector. The built-in shorting bar will automatically short the squib terminals on disconnection, preventing any stray current reaching the squib during the repair.
• 4
  Remove the Knee Airbag ModuleUnbolt the knee airbag module from its mounting bracket using the correct fastener size. Handle the module carefully — even a non-deployed inflator must be treated as live pyrotechnic equipment. Place it face-up on a flat, stable surface away from the vehicle.
• 5
  Fit the Replacement Module & ReconnectInstall the new OEM knee airbag module onto the mounting bracket and torque fasteners to specification. Reconnect the yellow SRS connector — push firmly until the secondary lock clicks fully into place. Refit the lower dashboard trim.
• 6
  Re-enable SRS & Clear the CodeReconnect the battery and refit the SRS fuse. Use MUT-III to clear B1632 and perform an SRS system check. Confirm the SRS warning light extinguishes and the knee airbag squib circuit reads within the specified resistance range.

Repair Path B: SRS Harness Open Circuit Repair

• 1
  Disable SRS & Trace the Fault LocationWith SRS disabled and using a break-out box, isolate which segment of the squib harness has the open — between the module and the first intermediate connector, or between that connector and the SRS ECU. This narrows the physical search area significantly.
• 2
  Locate & Repair the OpenCarefully route out the SRS harness in the identified segment. Locate the break — typically a chafed section, a pinched wire at a routing clip, or a corroded intermediate connector. Repair using OEM-specification SRS harness repair kit — do not use generic solder splices on SRS squib circuits without confirming this is permissible per the workshop manual for your variant.
• 3
  Verify, Re-enable & ClearBefore refitting any trim, use the break-out box to confirm the squib circuit resistance is within specification with the repair completed. Reconnect power and SRS fuse, clear B1632 with MUT-III, and confirm the SRS warning light extinguishes.

Repair Cost Estimates

Repair	Parts Cost (est.)	Labour (est.)	Total (est.)	DIY Difficulty
SRS connector cleaning & reseating	€0–€10	0.5 hr	€0–€60	Medium — SRS safety protocols required
SRS harness open circuit repair	€10–€50	1–3 hr	€60–€250	Hard — requires SRS break-out box and wiring expertise
Driver knee airbag module replacement (OEM)	€200–€500	1–2 hr	€260–€620	Hard — SRS specialist recommended
SRS ECU connector pin repair	€5–€30	1–2 hr	€55–€200	Hard — requires SRS break-out box

Prevention & Maintenance Tips

• Never disconnect or reconnect SRS connectors with the ignition on — always follow the full SRS disable procedure before touching yellow SRS connectors
• Inspect SRS harness routing whenever doing dashboard or steering column work — squib wiring pinched behind a bracket or caught under a trim clip is a common cause of B1632 after interior repairs
• Use OEM or OEM-quality replacement inflators only — aftermarket airbag inflators may not meet the squib resistance specification the SRS ECU monitors, causing a new fault code immediately after installation
• Always clear and verify SRS codes after any dashboard or interior repair — an SRS warning light left illuminated after unrelated work is a liability and a legal roadworthiness issue
• Address the SRS warning light promptly — a degraded SRS system cannot be relied on to provide full occupant protection in a collision

Frequently Asked Questions

Can I drive my Mitsubishi with B1632 stored?

The vehicle remains driveable, but the driver knee airbag cannot be guaranteed to deploy in a collision. In many markets a permanently illuminated SRS warning light is also a roadworthiness failure point. The fault should be diagnosed and repaired as soon as possible.

Is B1632 dangerous to diagnose at home?

Diagnosing B1632 requires working near live pyrotechnic components. With the correct SRS disable procedure followed precisely — SRS fuse removed, battery disconnected, 60-second wait observed — the risk of accidental deployment is effectively eliminated. The key danger is improper procedure: skipping the wait time, probing squib terminals with a standard multimeter, or reconnecting SRS connectors before the system is fully disabled.

Can I test the squib with my multimeter to confirm it has failed?

No. Using a standard digital multimeter directly across squib terminals is a recognised deployment hazard. Even the small current from a DMM ohms measurement can theoretically fire a squib. Only use an approved SRS squib resistance simulator or a dedicated SRS break-out box designed specifically for this purpose.

Will clearing B1632 without a repair fix the SRS warning light?

No. B1632 is a current fault — the SRS ECU actively monitors the squib circuit every ignition cycle. The code and SRS warning light will return immediately after clearing if the open circuit has not been repaired.

Can an aftermarket airbag inflator be used to replace the knee airbag?

Aftermarket inflators should be treated with caution on SRS systems. The squib resistance specification is narrow and inflator-specific. An incorrectly specced replacement may generate a new fault code immediately or — more seriously — may not perform to OEM deployment standards in a collision. OEM or OEM-equivalent parts are strongly recommended for all airbag inflator replacements.

Does the SRS ECU need to be replaced if B1632 keeps returning after a new inflator?

Only if thorough circuit tracing has confirmed continuity from the inflator connector all the way to the SRS ECU connector pins with no open present anywhere in the harness. The ECU is the last component to suspect — pin corrosion or spread terminals at the ECU connector is more common than an internal ECU fault and should be checked carefully before condemning the module.

How long does a knee airbag inflator replacement typically take?

For a technician familiar with the procedure and armed with the correct workshop manual, access and replacement of the driver knee airbag module on most Mitsubishi models takes approximately one to two hours, with the majority of the time spent on lower dashboard trim removal and refitting. Code clearing and SRS verification adds a further 15–20 minutes.

Conclusion

Mitsubishi B1632 – Driver Knee Airbag Squib Open Circuit is a high-severity SRS fault that must be diagnosed and repaired promptly. The most common causes are a failed inflator squib, a corroded or unseated yellow SRS connector, or a wiring open in the squib harness — often introduced during previous dashboard or steering column work. Always follow the full SRS disable procedure before working on any component, use an approved break-out box for resistance measurement, and use MUT-III to confirm circuit integrity and clear the code after repair.