Hyundai P1690 Code: Immobilizer SMARTRA No Response
The engine computer asked the SMARTRA immobilizer unit to check your key and got no answer back.
At a glance
Severity: Moderate
- Meaning
- Immobilizer SMARTRA No Response
- System
- ECU & Outputs · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $0–$1,800
- DIY difficulty
- Moderate
Hyundais with a conventional turn-key ignition use a small SMARTRA immobilizer unit mounted by the ignition cylinder. It powers the antenna ring around the lock, reads the chip in the key at 125 kHz and reports the result to the engine computer over a dedicated data line. P1690 means the ECM sent its request and SMARTRA never replied, so the ECM cannot confirm a valid key and blocks fuel injection. The fault sits between the ECM and the SMARTRA box, not in the key itself, which is why a spare key usually doesn't help. It is a well-known no-start cause on Accent, Elantra, Sonata NF/YF, Tucson and Santa Fe models with a metal key.
Can I keep driving? If the engine is already running it will keep running, but it may refuse to restart anywhere you switch it off. Drive straight to a shop or home and avoid stops where a no-start would leave you stranded.
How to read P1690
- P Powertrain
- 1 Manufacturer-specific
- 6 Computer & outputs
- 90 Specific fault
Symptoms
- Engine cranks normally but never fires, or fires and dies after a second or two
- Key-shaped immobilizer indicator in the cluster flashes instead of going out
- Problem comes and goes, often worse in heat, cold or damp weather
- Spare key behaves exactly the same as the main key
- Check engine light may stay off even though P1690 is stored in the ECM
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failed SMARTRA unit at the ignition cylinder (internal electronics or cracked solder joints)
- Loose, corroded or pushed-back pins at the SMARTRA or antenna connector under the steering column cover
- Open or shorted SMARTRA power, ground or communication wire, often after steering column work
- Low battery voltage during cranking so SMARTRA resets before it can answer
- Aftermarket remote starter or alarm interface wired into the immobilizer line
- ECM fault on the immobilizer communication circuit
Diagnosis step by step
Check battery voltage first
Measure at the battery: at least 12.4 V at rest and no dip below about 9.6 V while cranking. A weak battery makes SMARTRA drop out mid-conversation and can set P1690 on its own.
Tools: Multimeter
Read codes and immobilizer status
Read the ECM codes and, if your scan tool supports Hyundai immobilizer data, the key status. P1690 alone points at SMARTRA or its wiring; P1693 alongside it suggests the key chip is also not being read.
Tools: OBD-II scanner
Try the spare key once
A spare key that starts the car points back to the key, not to SMARTRA. If both keys fail with P1690, stop swapping keys and look at the SMARTRA side.
Inspect the SMARTRA connector
Remove the lower steering column shroud and find the small SMARTRA box next to the ignition cylinder with its antenna ring. Unplug, look for green corrosion or loose terminals, reseat firmly and try to start again.
Tools: Screwdriver, Flashlight
Check power, ground and the data line
With the connector back-probed and ignition on, SMARTRA should see battery voltage on its supply pin and less than 0.1 V drop on ground. Check the communication wire to the ECM for continuity and for a short to ground with the battery disconnected.
Tools: Multimeter
Replace and register SMARTRA
If power, ground and wiring are good, replace the SMARTRA unit. A new unit must be matched to the ECM and the keys with a Hyundai-capable scan tool and the vehicle's immobilizer PIN, so plan for dealer or locksmith programming.
Tools: OBD-II scanner
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean and reseat SMARTRA connector | Yes | $0–$100 |
| Battery replacement | Yes | $150–$280 |
| Repair SMARTRA or immobilizer wiring | No | $120–$350 |
| Replace SMARTRA unit including key/ECM registration | No | $300–$650 |
| Replace and program ECM (rare) | No | $900–$1,800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Kia
Kias with a turn-key ignition use the same SMARTRA hardware and set the same P1690, so the diagnosis on a Rio, Forte, Soul or Sportage follows the same path.
Emissions / smog test impact
Depends
P1690 is not an emissions fault and often doesn't light the check engine light, so a running car usually passes a state OBD test; a car that won't start can't be tested at all.
Frequently asked questions
Why doesn't my spare key fix P1690?
Because the key isn't the part that stopped answering. P1690 means the SMARTRA unit itself is silent, so every key gives the same result until SMARTRA, its wiring or its power supply is fixed.
Can I just unplug the immobilizer?
No. Without an answer from SMARTRA the ECM keeps fuel injection disabled, so unplugging it guarantees a no-start. Bypass modules exist, but they weaken theft protection and can cause insurance trouble.
Can a locksmith fix this instead of the dealer?
Many automotive locksmiths can replace SMARTRA and register keys on Hyundais if they have the right programming tool and can obtain the PIN. Ask beforehand whether they support your exact model.
It started fine after I wiggled the key. Is that a clue?
Yes. If movement at the ignition makes the difference, suspect the SMARTRA connector or antenna wiring near the column, which flexes when the key is turned.
Sources
- Manufacturer public service information (cross-checked)
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy