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Comparison · Bluetooth for Android

Generic Bluetooth ELM327 vs Konnwei KW903: differences

Two Bluetooth adapters for Android and Windows that do the same job on the car. One is the generic PIC18F25K80 adapter; the other, a Konnwei with all five OBD2 protocols and automatic power-off.

By Redacción de Satkit Updated 3 min read

Which one to choose for your case

If you just want to read and clear fault codes

ChooseELM327 Bluetooth OBD2 v1.5 €8.60

It costs quite a bit less and has the PIC18F25K80 chip, the one in the best-rated clones.

If you will leave it plugged in

ChooseKonnwei KW903 Bluetooth €14.76

It switches itself off after 30 minutes idle, so it does not drain a parked car's battery.

If you want a brand that states its protocols

ChooseKonnwei KW903 Bluetooth €14.76

Konnwei states all five OBD2 protocols it supports, from CAN to J1850.

Side by side

Generic Bluetooth ELM327 vs Konnwei KW903: differences: ELM327 Bluetooth OBD2 v1.5 / Konnwei KW903 Bluetooth
Feature ELM327 Bluetooth OBD2 v1.5Konnwei KW903 Bluetooth
ConnectionClassic BluetoothClassic Bluetooth
Works with
  • iPhone (not compatible)
  • Android
  • Windows
  • iPhone (not compatible)
  • Android
  • Windows
ChipPIC18F25K80Konnwei electronics
ProtocolsThe standard OBD2 ones: CAN, KWP2000, ISO 9141 and J1850All five OBD2: CAN (ISO 15765-4), KWP2000, ISO 9141-2, J1850 VPW and PWM
CAN busHS-CAN onlyHS-CAN only
Best forGetting started on an Android phone: fault codes and engine dataAndroid with a known brand and automatic power-off
Price at Satkit€8.60€14.76

Pros and cons

ELM327 Bluetooth OBD2 v1.5

Pros

  • PIC18F25K80 chip
  • Simple: pairs like any Bluetooth device
  • Works with Torque, Car Scanner and MotoScan on Android
  • Compatible with TuneECU (full ELM327 with the 25K80 chip)

Cons

  • Does not work with iPhone or iPad
  • HS-CAN only: cannot see the MS-CAN on Ford and Mazda

Konnwei KW903 Bluetooth

Pros

  • Konnwei brand, with all five OBD2 protocols
  • Switches itself off after 30 minutes idle
  • Compact: 49 × 35 × 22 mm

Cons

  • Does not work with iPhone or iPad
  • Costs more than a generic Bluetooth ELM327

For an Android phone or a Windows laptop, a classic Bluetooth ELM327 is the simplest choice. Both of these are, and with an app such as Torque or Car Scanner they do the same job: read and clear engine fault codes, turn off the warning light and show live data. The question is whether the brand is worth the extra money to you.

What they have in common

  • Classic Bluetooth: Android and Windows, not iPhone or iPad.
  • HS-CAN only: both reach the car's main network, not the MS-CAN on Ford and Mazda.
  • Same apps: Torque, Car Scanner or OBD Auto Doctor. For BMW motorcycles with MotoScan, the v1.5.

How they differ

Generic with a known chip, or a brand

The ELM327 Bluetooth v1.5 is generic, but you know what is inside: the PIC18F25K80 microcontroller, the one in the clones that diagnostic forums rate best. The Konnwei KW903 is made by Konnwei, a well-known diagnostic tool brand that publishes the protocols it supports.

Protocols

Konnwei states all five OBD2 protocols: CAN (ISO 15765-4), KWP2000, ISO 9141-2, J1850 VPW and PWM. The v1.5 covers the same standard OBD2 protocols. For a European petrol car from 2001 or diesel from 2004 onwards, either one speaks its language.

Automatic power-off

The KW903 switches itself off after 30 minutes idle. If you will leave it plugged in, that is a point in its favour. With the v1.5, unplug it when you are not using it.

Price

The generic one costs quite a bit less (the prices above update with each product page). For the difference, the KW903 gives you the brand and automatic power-off.

What if I have an iPhone?

Neither will do. With an iPhone you need a Wi-Fi adapter: we compare them in ELM327 Wi-Fi vs Vgate iCar2. And if you are unsure about connections, see Bluetooth, Wi-Fi or USB.

Frequently asked questions

Is the Konnwei KW903 an ELM327?

Yes, it presents itself to apps as an ELM327, so it works with the same programs: Torque, Car Scanner and the other OBD2 apps for Android and Windows.

Which is better for an older car?

Both cover the older OBD2 protocols, ISO 9141 and KWP2000. If your car is from 2001 to 2005, either is a good choice; the one to avoid for those years is the ELM327 v2.1 HH.

Do they work with an iPhone?

No. Both are classic Bluetooth, which iOS does not let these apps use. For an iPhone you need a Wi-Fi or Bluetooth 4.0 adapter.

Which one can I leave plugged into the car?

The Konnwei KW903, because it switches itself off after 30 minutes idle. Unplug the generic one if the car will sit for several days.

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