What the customer told us
Red triangle warning light, sudden drop in fuel economy, and the engine running constantly instead of switching over to electric. The dealer quoted a complete hybrid battery pack.
What we found
Codes pointed at a battery block voltage imbalance. We pulled the pack and tested every module individually under load. Twenty-six of the twenty-eight blocks were within spec. Two blocks were dropping well below the rest under discharge, which is what triggers the warning and forces the car to run on gas.
What we did
Replaced the two weak modules with tested-matched units, cleaned and re-torqued every bus bar connection, replaced the battery cooling fan filter which was completely packed with dust, and rebalanced the pack.
How it came out
Warning cleared and stayed off. Fuel economy went from about 31 mpg back up to 47 on his normal commute. He spent roughly a quarter of the dealer quote and has driven it two years since.
Parts fitted
- 2 x hybrid battery modules
- Cooling fan filter
- Bus bar hardware
Photos to add: Red triangle warning on the dash; Hybrid pack out and opened for module testing; Load testing each block individually; Rebalanced pack reinstalled and cleared.
