My Kia K900 lights up with warnings and won't shift into gear. What's wrong?

Short answer: Start with the battery: clean and tighten both terminals and have the battery load-tested. A weak connection can make every module throw warnings at once. If that's fine, the car needs a dealer to look for a module communication (CAN) fault. Also run your VIN for the HECU recalls (22V051000 and 23V652000), which cover a brake module that can short and cause a fire. And check the trunk for water, which can damage wiring.

Symptom: Many warning lights appear at once, the car won't shift into gear, the A/C stops cooling and it limps at low speed. Then it goes back to normal and repeats.

What to check first

1. Clean and tighten the battery terminals and grounds.
2. Load-test the battery.
3. Look for water in the trunk and around wiring.
4. Have the codes read in all modules, not just the engine.
5. Run your VIN at nhtsa.gov/recalls for 22V051000 and 23V652000.

Likely causes

1. Loose or corroded battery connections. A bad connection can make voltage drop for a moment, and the computers react with a flood of warnings.
2. Module communication (CAN) fault. CAN is the network the car's computers use to talk to each other. A fault in it can set warnings all at once and block shifting.
3. ABS/traction control module fault (recall). The HECU is the anti-lock brake module. Kia recalled some K900s because it can short and cause a fire.

What it usually costs

Owners in these threads didn't post prices. Battery work is cheap; network diagnosis can take hours of labor.

Is it safe to keep driving?

If it won't shift or limits speed, don't drive it in traffic. If you smell burning or see smoke from the engine bay, get away from the car and call 911,.

DIY or shop?

Battery terminals and testing are DIY. Network diagnosis and recall work are dealer jobs.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists 22V051000 (some 2016-2018 K900s) and 23V652000 (some 2015-2018 K900s): the hydraulic electronic control unit (HECU), the anti-lock brake module, can short and cause an engine compartment fire, even while parked. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 49 keyword-matched complaints for Kia K900 2015–2020 (of 68 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-31; keywords: suspension, air, sag, battery, electrical, drain). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 2016 Kia K900 on Reddit r/carproblems, a 2016 K900 owner said the car started fine, then a flood of warnings came on. While they were on, it wouldn't shift into any gear, the A/C stopped cooling and it would only creep to about 10 mph. It came and went every few minutes. Commenters said check the battery connections and condition first, and one said it looked like a CAN communication fault needing dealer diagnosis.
• In K900 on Reddit r/kia, a buyer looking at a 2016 K900 asked about issues. Owners mentioned electrical gremlins and air suspension problems as they age, and one called the first-generation car a money pit for parts. The buyer passed after finding the trunk still wet from a leak the dealer said was fixed.

Quick tip

When everything goes off at once, think power and ground before you think 'every module failed.' And don't skip that recall check. The HECU one is a fire risk.

Vehicle focus: Kia K900, 2015-2020.

Safety / mechanic note

Fire-risk recalls and a car that won't shift are safety items. Verify with a mechanic.