Check Engine Light is on on 1991 Lexus ES250

Diagnostic code is showing as 5271. What is the problem?

Asked by for the 1991 Lexus ES250
Bridging the T1 and E1 connector in the diagnostic connector if you are counting the "flashes of the Check Engine Light correctly you are getting a code 52 which is Knock sensor code, on that engine it is frequently the short harness that attaches to the sensor in the Valley of the engine that fails, code 71 is EGR system malfunction usually a failed modulator blocked passages or a failed temperature switch at the EGR.