I have a 89 p/up 22re. The cel light shows codes 51 and 71. Switch sensor and egr system. Codes found here. www.troublecodes.net/Toyota/ How important are these the fix right away? Are they a PITA to replace? What is the switch sensor? Does that mean I have to replace the egr valve? Yotatech has helped me with many things before. Thanks folks!

 

Did you try disconnecting the battery to clear these codes? Code 51 and 71 are retained in the memory of the ECM. I recently had a code 51 after a long battle with a no spark condition with my 3.0 and I took about three or four times to clear it.http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf
look at pg. EG1-113 it will explain what I said.

 

I cleared the codes and drove about 50 miles. No new code. The engine ran fine before the light came on. It still runs good. I'll run some seafoam through it and some throttle body cleaner. Thanks.

 

OK. now the codes are back. Truck runs fine just those codes pop up about every 500 miles or so. Any suggestions?

 

71- two things can cause that. the engine reaches operating temp and the ECU tries to open the EGR valve but the temp sensor on the EGR valve isn't up to the right temp, or the engine reaches operating temp and the ECU tries to open the EGR valve but the temp sensor on the EGR valve isn't up to the right temp. the first one could be a faulty temp sensor on the EGR valve and the second one could be a restricted EGR passage.
51 is a "switch signal" meaning, IIRC, the TPS is not signalling IDL to the ECU, the clutch switch was on or the a/c was on.... but I could be wrong.

 

Thanks for the suggestions. It did pass a smog check about 100 miles after clearing the codes.