Code
U2173
OPEL
U — Network/User
CAN-Bus No Communication with PEPS(Open&Start)
Views:
UK: 6
EN: 7
RU: 5
AI status
Completed
Completed
100%
Causes
- PEPS module internal failure
- PEPS module not powered (fuse, supply, ground)
- Damaged CAN bus wiring or connector between PEPS and gateway/BCM
- Faulty gateway/BCM or other intermediate module
- Low vehicle or key fob battery preventing PEPS operation
- Intermittent corrosion or poor connector contact
Symptoms
- Keyless entry or push-button start not working
- Vehicle may not recognize key fob, inability to unlock/lock or start
- Warning lamp or message on dash indicating key/immobiliser fault
- Other modules reporting lost communication with PEPS
- Intermittent operation of PEPS functions
What to check
- Attempt to reproduce fault: confirm PEPS functions fail consistently
- Check vehicle and key fob battery voltages
- Scan vehicle network with OEM scan tool to see which modules appear and whether PEPS is listed
- Inspect fuses and relays related to PEPS power circuits
- Visually inspect PEPS connector(s) and CAN wiring for damage, corrosion or disconnection
- Check for other communication-related DTCs that may point to gateway/BCM or wiring issues
Signal parameters
- CAN High voltage (idle ≈ 2.5 V; dominant ≈ 3.5 V) at PEPS connector pin
- CAN Low voltage (idle ≈ 2.5 V; dominant ≈ 1.5 V) at PEPS connector pin
- Presence and frequency of PEPS CAN message ID(s) on network (messages/sec)
- Supply voltage to PEPS (ignition/accessory/rest states)
- Ground continuity and voltage drop under load
- Key fob RF wake signals (where monitorable) and PEPS wake events
Diagnostic algorithm
- Verify customer complaint and note conditions when fault occurs (ignition state, distance of key, battery low).
- Check and record vehicle battery and key fob battery voltages; replace if low.
- Connect OEM diagnostic tool, read live data and confirm U2173 plus any related network codes. Check if PEPS module appears in module list.
- Inspect fuses, relays and connectors for PEPS power and ground; repair any open or corroded connections.
- With ignition off, visually inspect CAN wiring and connectors between PEPS, gateway/BCM and junction points for damage or corrosion. Repair as required.
- Measure CAN-H and CAN-L at the PEPS connector and at the gateway with ignition in the appropriate state. Look for correct idle voltages and dominant/recessive transitions using scope or CAN tester.
- If physical layer is OK but messages absent, trace toward the gateway/BCM: check for presence of PEPS messages at gateway. If messages present at PEPS but not at gateway, suspect gateway or network splice.
- Check for excessive bus load or missing termination (measure bus impedance). Repair short/open/termination faults.
- If a suspected module is non-responsive and wiring checks good, consider reflashing/updating module software per OEM bulletin before replacement.
- Replace module only after confirming module fault via diagnostics or by substituting a known-good unit. Clear codes and retest all functions over drive cycles to confirm repair.
Likely causes
- Blown fuse or missing power/ground to PEPS
- Loose, corroded or disconnected connector at PEPS or gateway
- CAN high/low shorted or open on branch to PEPS
- Dead key fob battery preventing PEPS activity
- Gateway/BCM not forwarding PEPS CAN messages due to failure
Fault status
Status
No communication with PEPS (Passive Entry Passive Start) on CAN bus — messages/timeouts from PEPS not received by gateway/BCM.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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