B2A10

Code

Generic B — Body

Passive Entry/Start System — Transmitter Signal Weak

Brand: Generic

Type: B — Body

Views: UK: 19 EN: 26 RU: 26

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Weak or dead key/transmitter battery
Damaged or corroded key fob or antenna inside the fob
Faulty vehicle receiver/antenna module or wiring/connectors
Poor antenna grounding or broken antenna coil
RF interference from aftermarket electronics or nearby transmitters
Poor key programming or transmitter mismatch

Symptoms

Intermittent or delayed passive unlocking/locking
Push-button start not recognizing key unless fob is very close
Warning or notification on dash: "Key not detected" or similar
Reduced effective range of the key fob
Inconsistent LED blink or transmit behavior on the fob
Multiple attempts required to lock/unlock or start vehicle

What to check

Verify DTC stored and capture freeze‑frame and occurrence count
Check the key fob battery voltage with a multimeter (replace if low)
Try a known-good spare key/transmitter to compare behavior
Visually inspect key fob for damage, corrosion, or water ingress
Inspect vehicle receiver/antenna connectors and wiring for corrosion, damage, or loose pins
Check vehicle battery voltage and module supply voltages (~12 V nominal)

Signal parameters

Passive entry systems typically use a low‑frequency (LF) wake signal plus a UHF transmitter; common RF/frequencies: LF ~125 kHz (wake/coil), UHF ~315 MHz or ~433 MHz (region dependent)
Expected transmitter battery voltage: typical coin cell CR2032 ≈ 2.8–3.2 V (replace below manufacturer minimum)
UHF receive sensitivity is typically in the -80 to -100 dBm range (manufacturer dependent); a significantly lower RSSI indicates weak transmit signal or antenna issue
LF wake coil field should activate within expected proximity (usually < 30 cm from antenna coil); no LF pulse or weak LF indicates antenna/coil fault
Packet error or CRC fail rate should be very low; elevated packet errors imply RF interference or low signal strength

Diagnostic algorithm

Confirm the fault: read DTC B2A10 and note freeze frame/occurrence. Verify symptoms with the customer.
Check and record vehicle battery voltage and key fob battery voltage. Replace key battery if below specification and retest.
Use the spare/transponder key: if spare works normally, suspect the original transmitter (battery or hardware).
Inspect the transmitter for damage/corrosion; open fob (if serviceable) and inspect antenna/contact solder joints.
Operate the fob at close range to the LF antenna/receiver location (door handle/pillar and push‑button area). If only works when touching receiver area, suspect low transmit power or antenna fault.
Inspect wiring and connectors for the passive entry antenna/receiver module. Check continuity of antenna coil and measure resistance per service info.
With appropriate RF diagnostic tools (service scanner with keyless module data or RF analyzer), observe LF wake pulses and UHF transmit bursts and RSSI. Compare to expected ranges.
Check for and remove potential RF interference sources (temporarily disconnect aftermarket devices). Reattempt operation.
Reprogram/relearn the key/transmitter per manufacturer procedure and clear DTCs. Retest for reoccurrence.
If transmitter still weak and spare works, replace faulty transmitter. If both transmitters weak, replace or repair vehicle antenna/receiver module and retest.
If module replacement performed, verify programming, clear codes, and perform full functional test before returning vehicle.

Likely causes

Key fob battery below recommended voltage (most common)
Physical damage to the transmitter or water ingress
Connector corrosion or open/short in antenna feed/wiring
Receiver/antenna module failure or mounting displacement
Strong external RF interference in the vehicle environment

Fault status

⚠️ Status

Transmitter signal weak — passive entry/start transmitter is sending a signal below expected strength or intermittently; check transmitter battery, fob hardware, vehicle antenna/receiver and for interference.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.0 hours