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LLY - P2149 (Injector Positive Voltage Relay Control Circuit Group 2)

Texas Diesel Company has the factory GM computer in-house! This allows us to quickly and effectively diagnose your vehicle saving you both time and money. We are also able to provide in-house programming of all components & modules installed in your vehicle, no different than the Chevrolet/GMC dealership would. If you’re another local shop interested in having us re-program a module for you, please call (903) 292-0400

We’ve seen this code in our shop a few times and its never a fun one to diagnose. Essentially what the computer is telling you is that there’s a connectivity issue with an injector. Typically when this code presents itself it will throw a fault for cylinders 2 (P0202), 3 (P0203), 5(P0205), or 8(P0208) respective to which cylinder is causing the issue. Furthermore, the vehicle will disable all injectors on said circuit (2,3,5,8) until the problem is fixed. The FICM controls each injector by grounding the circuit to said injector, causing it to energize. When an injector has an issue energizing, it sets a fault code and the vehicle will enter limp mode to save the engine from further damage. GM has put out many service bulletins on this issue and they have a “fix for the problem”. Replacing the connector on said injector will most- likely solve your problem but in some cases, an entire engine harness may need to be replaced to fix the problem. GM has found that the connectors can sometimes become worn out and be to blame. The most difficult part of solving this problem is that

the issue doesn’t always lie in the connector. A chaffed wire in the harness can also be to blame, and it may not present itself as an issue at all times. The best way to fix a wiring harness in this case it to remove the wiring harness from the vehicle, take off all the shielding and trace down each wire checking for chafing or weak spots in the wire. This will be a very time consuming process and in this case we would recommend replacing the harness with a new one from GM, if available.


P1246 (Injector Positive Voltage Relay Control Circuit Group 1) may also present itself and the diagnosis is very similar to that of P1249. P1246 is referring to injectors/cylinders 1 (P0201), 4 (P0204), 6 (P0206), or 7 (P0207). Make sure to check that your FICM is bolted down to its bracket securely and ensure that both connectors as well seated & in the locked position.

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