00931 – Lock unit for central locking right rear – implausible signal (Volkswagen)

Volkswagen-specific code — factory diagnostic data

Last updated: March 31, 2026

Definition source: Volkswagen factory description · Autel MaxiSys Ultra & EV. Diagnostic guidance is based on factory-defined fault logic for this code.

00931 means the right rear door may not lock or unlock reliably. You might also see the door status act wrong on the dash, even when the latch seems closed. According to Volkswagen factory diagnostic data, this code indicates an implausible signal from the lock unit for the right rear central locking. That “implausible” wording matters. The module sees a lock/latch input that does not match what it expects during a lock, unlock, or safe-lock command. This fault usually points to a latch microswitch signal, wiring at the door, or a mechanical latch that does not reach its end positions.

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00931 Quick Answer

Volkswagen DTC 00931 sets when the central locking system sees an implausible signal from the right rear lock unit. Confirm the latch/lock switch signals and door wiring before replacing the lock unit.

What Does 00931 Mean?

Official definition: “Lock unit for central locking right rear – implausible signal.” In plain terms, the central locking system cannot trust the right rear latch feedback. The car commands a lock or unlock, but the right rear lock unit reports a position or door status that does not make sense. That mismatch can prevent normal locking, enable repeated re-lock attempts, or cause incorrect “door open” indications.

What the module checks and why it matters: On Volkswagen platforms, the convenience/central locking logic monitors latch state and lock position feedback from the right rear door. It expects those signals to change in a specific order and timing window. An “implausible” result means the signals conflict with each other, conflict with the command, or flicker between states. That points diagnosis toward inputs and wiring integrity first. SAE J2012-DA guidance applies here: the DTC identifies a suspected trouble area. It does not prove the lock unit has failed.

Theory of Operation

During normal operation, the Volkswagen central locking system sends lock and unlock commands. The right rear lock unit then moves an internal motor and linkage. The latch also reports status through internal switches. Common signals include door closed, lock position, and safe-lock status, depending on platform.

00931 sets when the control module compares commanded action to feedback and sees a contradiction. A worn latch can hang between positions. A switch can bounce or stick. Wiring at the door hinge can add resistance or open intermittently. Any of those faults can create an “implausible” state, even when the lock sometimes works.

Symptoms

You typically notice a right rear door locking or status problem first.

• Locking failure Right rear door will not lock, unlock, or both
• Intermittent operation Works sometimes, then fails after bumps or door movement
• False door-ajar Cluster shows a door open when it is closed
• Re-lock cycling Vehicle locks, then immediately unlocks or re-locks repeatedly
• Remote/key issues Remote unlock works for other doors but not right rear
• Interior button behavior Central lock switch gives inconsistent results
• Battery drain Comfort system stays awake due to incorrect door status
• Alarm concerns Alarm may trigger due to incorrect latch reporting

Common Causes

• High-resistance latch connector at the right rear door: Corrosion or a loose terminal skews the lock feedback signal and the module flags it as implausible.
• Broken wire in the door jamb harness: Repeated door movement cracks conductors, which creates intermittent opens that confuse the lock position reporting.
• Short to ground in the lock signal circuit: Chafed insulation lets the signal collapse low during actuation, so the reported state does not match the command.
• Short to battery in the lock signal circuit: A rubbed-through harness can hold the signal high, so the module never sees a valid transition.
• Poor power or ground feed to the lock unit: Voltage drop under load slows the motor and corrupts internal switch readings during lock/unlock.
• Water intrusion into the right rear lock unit: Moisture contaminates the internal microswitches and electronics, which creates erratic or conflicting feedback states.
• Mechanical binding in the latch/lock mechanism: A sticking linkage prevents full travel, so the switch state disagrees with the commanded position.
• Incorrectly seated connector after door or latch work: A partially latched plug or backed-out terminal causes intermittent plausibility failures right after service.

Diagnosis Steps

Use a scan tool that can access Volkswagen body/central locking data, not just generic OBD. Have a DVOM, a test light or fused jumper, and back-probing tools. A wiring diagram and connector views matter here. Plan to do voltage-drop testing under load at the lock unit. If the fault acts intermittent, use scan-tool snapshots during repeated lock cycles.

1. Confirm DTC 00931 and record all related body/central locking DTCs. Save freeze frame data if available, and note battery voltage, ignition state, and any “lock command” or “door status” values at the moment the DTC set.
2. Do a fast visual inspection before any meter work. Check the right rear door jamb boot, harness routing, latch area, and any signs of water intrusion. Inspect fuses and power distribution that feed the central locking/comfort functions, and verify the vehicle battery condition.
3. Decide how urgent the fault is by its status. A hard fault in a continuously monitored circuit typically returns immediately on key-on or the first lock command. A pending or sporadic fault points to wiring movement, moisture, or a marginal connector.
4. Use the scan tool to view live data for the right rear door. Watch door ajar and lock/unlock status while commanding lock and unlock. If the command changes but the feedback stays fixed or contradicts the command, treat it as a plausibility problem in the latch feedback circuit or latch mechanics.
5. Run an output test or basic setting, if your scan tool supports it, to cycle the right rear lock. Repeat the test while gently flexing the door jamb harness. If the status flips or drops out during movement, focus on a broken conductor or terminal fit.
6. Verify power and ground at the lock unit under load using voltage-drop testing, not continuity alone. Command the lock while measuring from battery positive to the lock power feed, then from the lock ground to battery negative. Keep ground drop under 0.1 V with the circuit operating.
7. If power/ground checks pass, test the signal and control circuits for opens and shorts. Back-probe at the lock connector and compare the signal behavior during lock/unlock to the left side, if equipped similarly. Do not rely on static key-off readings for a dynamic plausibility fault.
8. Check connector integrity closely. Look for spread terminals, pushed-back pins, moisture, or green corrosion at the right rear latch connector and the body-side connector. Perform a light tug test on each wire and verify the connector locks fully.
9. Separate mechanical from electrical causes. With the trim removed, inspect linkage and latch movement while commanding lock/unlock. A latch that stalls, binds, or fails to reach end travel can create an implausible feedback even with perfect wiring.
10. If you suspect an intermittent condition, use two data methods. Freeze frame shows the conditions when the DTC set. A scan tool snapshot, triggered during repeated lock cycles or a road test, captures the live moment the signal becomes implausible.
11. After repairs, clear codes and run multiple lock/unlock cycles from all control points. Confirm the right rear lock status tracks commands every time. Recheck for returning pending versus confirmed faults after at least one complete drive cycle.

Professional tip: Do not condemn the latch or module because the lock sometimes works. A high-resistance ground or a cracked jamb wire often passes a continuity test. Load the circuit during actuation and watch the scan tool at the same time. That combination catches the “implausible signal” root cause faster than parts swapping.

Possible Fixes

• Repair corroded or loose terminals at the right rear lock connector: Clean, tighten, or replace terminals after you verify abnormal voltage drop or unstable live data.
• Repair the right rear door jamb harness: Restore broken conductors or chafed insulation, then secure the harness to prevent repeat flex damage.
• Restore proper power/ground feeds: Correct fuse/connection issues and fix high-resistance grounds discovered during voltage-drop testing under load.
• Correct water intrusion causes: Repair the leak path, dry the connector area, and recheck signal stability before replacing components.
• Address latch binding or misalignment: Repair mechanical issues that prevent full travel so the feedback switch states match the commanded lock position.
• Replace the right rear lock unit only after circuit verification: Install a known-good lock unit when power, ground, wiring, and mechanics all check out yet the feedback stays implausible.

Can I Still Drive With 00931?

You can usually drive a 2013 Volkswagen Caddy with DTC 00931 because it targets the right rear central locking lock unit signal plausibility. The engine, brakes, and steering normally stay unaffected. The risk sits in security and occupant safety habits. A door that does not lock, does not unlock, or reports the wrong state can leave the vehicle unsecured. It can also trap a passenger if the door will not unlock from the inside or outside. Before driving, confirm the right rear door opens from inside and outside. Also confirm it latches fully and will not pop open. If the door ajar warning behaves erratically, treat the latch as suspect and avoid carrying rear passengers until you verify the latch and wiring.

How Serious Is This Code?

This code ranges from inconvenience to a real safety concern. It acts like an inconvenience when only remote locking or the key fob fails on the right rear door. It becomes more serious when the latch state disagrees with reality. An implausible signal means the module sees a lock/unlock or door-closed input that does not match the commanded position. That mismatch can disable selective unlocking, prevent alarm arming, or cause false alarm triggers. On some Volkswagen platforms, the body module also uses door status for interior lights and sleep logic. A false “door open” can drain the battery over time. If the right rear door fails to latch reliably, do not continue driving until you confirm mechanical latch integrity.

Common Misdiagnoses

Technicians often replace the right rear lock module first because the scan tool names it. That approach skips the root cause. Wiring in the door jamb frequently causes plausibility faults because it flexes every door cycle. Another common miss involves connector drag or water intrusion at the latch connector. High resistance can corrupt the signal and mimic a failed lock unit. People also misread freeze-frame style data and ignore that implausible means “inputs disagree,” not “component dead.” Avoid wasted spending by verifying power, ground, and signal integrity at the lock unit connector. Compare measured latch switch states to live data while you manually move the latch.

Most Likely Fix

The most common confirmed repair directions for 00931 involve fixing the right rear door harness or connector issues before any part replacement. Start with the door-to-body rubber boot area. Look for broken conductors, stretched wires, and damaged insulation. Clean and secure the latch connector and check for moisture or terminal tension problems. If tests prove the wiring stays stable and the signals still disagree with actual latch position, then the lock unit internal switches or electronics become a valid suspect. After repairs, verify by repeatedly locking and unlocking with the scan tool and the remote. Also cycle the door and confirm live data stays consistent under vibration and movement.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a sensor, a module, or the labor needed to diagnose the fault correctly.