C1203 on Toyota
Skid control ECU to engine computer communication malfunction (Toyota)
Severity: Inspect soon
Toyota's owner's manual says a slip indicator or ABS light that stays on means a fault in VSC, TRAC or ABS, and the car should be inspected immediately. With this code, traction and stability control cannot work with the engine as designed.
It gets more serious if:
- Stop: The red brake system warning light comes on or the brake pedal feels wrong. Toyota says to stop in a safe place and contact a dealer, because continuing to drive may be dangerous.
This page covers only what differs on Toyota. For what C1203 means, the ranked causes and the test order, see the C1203 guide.
What's different on Toyota
ToyotaYour car
2002–2004 · Sequoia
Supported by vehicle dataOwners report VSC, TRAC and ABS lights with C1203, often with C1223 or C1247; Toyota bulletin BR00203 covers the 2003 model. Whether it is still current is not verified.
2003 · 4Runner
Supported by vehicle dataToyota bulletin 00503: VSC light with C1203, corrected by a skid control computer logic change. Whether it is still current is not verified.
2010 · Tundra
Supported by vehicle dataA dealer readout lists C1203 as the ECM communication circuit, stored with deceleration sensor codes.
BR00203Status unverified
VSC communication between skid control computer and ECM, DTC C1203
2003sequoia · issued · NHTSA 10003953
Covers C1203 on the 2003 Sequoia; only the NHTSA summary was read.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
00503Status unverified
VSC light on with DTC C1203
20034runner · issued · NHTSA 10005760
A change to the skid control computer logic prevents the condition; only the NHTSA summary was read.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Sources and review
- Toyota BR002-03: VSC communication between skid control computer and ECM, DTC C1203
- Owner complaints: 2002-2004 Toyota Sequoia VSC, TRAC and ABS lights with C1203
- Toyota 00503: VSC light on with DTC C1203 in the skid control computer
- NHTSA complaint 10853402: 2010 Toyota Tundra, dealer codes C1203, C1232, C1336
- Camry Owner's Manual (OM06291U)
- 2005 Toyota Sequoia repair manual: translate ECU codes 51 and 53 (ECM control system and CAN1 communication)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error