codes 27 and 21
Thread Starter
Instructor
Joined: Mar 2003
Posts: 118
Likes: 0
From: Shrewsbury MA
codes 27 and 21
I have been having a problem with high idle (2000 RPMs) on a stock 94 with manual transmission. Checked for vacuum leaks, none found, Cleaned EGR valve, replaced TPS, IAC and all 3 O2 sensors. Now car is idling around 1200 RPMs. Pulled the codes and I get 27, 21, 64, 65, 66. I had 64, 65, 66 before I changed the IAC. Now that I changed the IAC I get 21 and 27 also. What do these mean?
Thanks for the help
Thanks for the help
Thread Starter
Instructor
Joined: Mar 2003
Posts: 118
Likes: 0
From: Shrewsbury MA
Update
Cleared codes and drove car for a while, Idle was normal. When I shut it off and restart the fast idle returns. Read codes again, got 21, 64, 65. Changed the TPS, cleared codes and restarted. Fast idle still and codes are 64 and 65 only. These codes never clear from the ECM. If I clear the codes, do not start the car and read codes again 64 and 65 are still there. Anyone with any suggestions. HELP please.
Cleared codes and drove car for a while, Idle was normal. When I shut it off and restart the fast idle returns. Read codes again, got 21, 64, 65. Changed the TPS, cleared codes and restarted. Fast idle still and codes are 64 and 65 only. These codes never clear from the ECM. If I clear the codes, do not start the car and read codes again 64 and 65 are still there. Anyone with any suggestions. HELP please.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I don't know if a 95 codes are the same as a 94 but:
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
First the codes will have to be cleared, then if the high idle still exist we'll start from that. You stated you changed the O2 sensors. Did you check the circuit to make sure it is sending the right signal to the PCM?
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
First the codes will have to be cleared, then if the high idle still exist we'll start from that. You stated you changed the O2 sensors. Did you check the circuit to make sure it is sending the right signal to the PCM?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Originally Posted by chb88
Thanks for the reply
No i did not check the circuit. How does one go about checking it?
No i did not check the circuit. How does one go about checking it?
First you need to find out if the 95 and 94 codes are the same. I would do a visual inspection of the wire (could be touching the exhaust or grounded). If the codes are the same a rich/lean on the same circuit is either a bad O2 sensor or faulty connection. They sell an adapter to put between the connection so you can check the volts. It ranges between .1v (lean) to .9v (rich). Or you can get a diagnostic scan to check voltage. I think if you replaced that O2 sensor with a new one and still have the same problem, then the circuit is problem.
