P2548
Torque Management Request Input Signal "B"
- Severity
- Medium
- Driving
- Drivable — book it in
A fault in torque management request input "B". This is the incoming side of the conversation: the transmission, traction control or stability system asking the engine module to reduce torque briefly - during a gear change, or to stop a wheel spinning. Without the request arriving, the two cannot coordinate.
Possible causes
- CommonWiring or bus fault between the modules
- CommonCorroded connector at either module
- CommonLow battery voltage dropping a module off the bus
- CommonFault in the transmission, ABS or traction control module
- PossibleSoftware mismatch after a module replacement
- RareFailed control module input
What you might notice
- Harsh or erratic shifting
- Traction control warning light
- Reduced power
- Hesitation during gear changes
- Check engine light on
What to check, in order
- Read all codes across every module the tool can reach. Torque management is a conversation between modules, so the fault is often at the other end.
- Check battery voltage and state of charge - a weak battery causes module communication faults with no wiring problem at all.
- Inspect the connectors at both modules.
- Ask whether a module was recently replaced or updated. A software mismatch produces exactly this and no amount of wiring diagnosis will find it.
- Check the wiring between the modules for damage.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Vehicle speed control, idle control and auxiliary inputs
P2500P2501P2502P2503P2504P2505P2506P2507P2508P2509P2510P2511P2512P2513P2514P2515P2516P2517P2518P2519P2520P2521P2522P2523P2524P2525P2526P2527P2528P2529P2530P2531P2532P2533P2534P2535P2536P2537P2538P2539P2540P2541P2542P2543P2544P2545P2546P2547P2548P2549P2550P2551P2552P2553P2554P2555P2556P2557P2558P2559P2560P2561P2562P2563P2564P2565P2566P2567P2568P2569P2570P2571P2572P2573P2574P2575P2576P2577