2002 Elantra P0121 code

https://repairpal.com/obd-ii-code-p0121

Po121 Tps sensor RPM, Po140 o2 sensor bank 1 sensor 2,Po171,172,101 MAF dirty sensor.

There are Technical Service Bulletins (TSBs) on many of the Elantras specifically related to hard or abrupt shifting when the transmission or weather is cold. You may need to take it to a Hyundai dealer to ensure the TSBs for the TCM related to shifting have been applied to your particular vehicle.

Did you replace the shift valves because of the trouble codes ?

I would say no,has to come apart

P0500 (Vehicle Speed Sensor) May limit the revs of the motor & auto may shift erraticly. P0121 (Throttle Posision Sensor) I would start with this as it can also cause transmition probs. I would just look at these 2

You can replace the transmission valve body as per the instruction or install a new TCC apply valve kit. However the installation requires for the valve body to be removed and honed out by a special tool. I wouldn't recommend this procedure unless you have the proper tools and the know how about the inner workings of the automatic transmissions.

#01-07-30-023B: Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body) - (Mar 22, 2002)
Subject: Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body)
Models: 1996 Buick Roadmaster
1996 Cadillac Fleetwood
1999-2000 Cadillac Escalade
1996-2000 Chevrolet Camaro, Corvette
1996-2000 Pontiac Firebird
1996-2000 Chevrolet and GMC Light Duty Truck Models
1996-2000 Oldsmobile Bravada
with 4L60-E Automatic Transmission (RPO M30)
Built Prior to January 15, 2000 (Julian Date 0015)

This bulletin is being revised to update VIN Breakpoint Date information and revise the Parts Information table. Please discard Corporate Bulletin Number 01-07-30-023A (Section 07 -- Transmission/Transaxle).

Condition: Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.

Diagnosis: Typically, these vehicles will have been driven more than 32,000 km (20,000 mi) before this condition occurs.

The scan tool may show a DTC P1870 set as a history code.

A harsh 1-2 shift or DTC P1870, caused by wear in the control valve body, may be difficult to duplicate when the transmission temperature is below 93°C (200°F).

Cause: The condition may be due to wear in the control valve body. This wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply.

Important:
• DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code.
• When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result.
• This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle).
• When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code.
• When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL).

Correction: Install a control valve body with the revised TCC regulator and isolator valves. Refer to the Parts Information table below. These valves are used in all transmissions produced after January 15, 2000 (Julian Date 0015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.

Important: If all of the following conditions are true, it is not necessary to rebuild the transmission or to replace additional transmission components beyond the control valve body.
• Transmission operation is normal before the transmission reaches operating temperature, or before DTC P1870 is set (no slips, flares, or missing gears).
• The torque converter is not blue or overheated.
• The transmission fluid is not burned or has no burned odor.
• The transmission fluid pan contains no abnormal debris (clutch material, bronze, brass, or metal fragments).

Keep us updated.

NO: 43-37
DATE: 2-25-2003
MODEL: MY 2001-2002 S60, V70, V70 XC
SUBJECT: Shift Quality Issues due to B4 Servo Cover Failure, 2-3 upshift harshness or flare
CHASSIS: These chassis breaks are approximate:
S60: 062000-152000
V70: 116000-230000
V70 XC: 036000-067100
TRANSMISSION SERIAL NUMBER: The first 3 digits of the serial number on the affected transmissions will be between 01C (March 2001) and 01L (December 2001).
DESCRIPTION:
In the AW 55-50, brake number four (B4), is only applied in 3rd gear. The B4 is applied by a piston, which is covered by an aluminum cap. This cap has a steel washer crimped to its inside surface, and a rubber cushion that sits between the cover and the washer.
If this washer breaks free from the crimps it will become concaved because of the B4 piston return spring pressure.
This loose washer can cause: - " 2-3 upshift flare / slip - " Harsh 2-3 upshifts - " 3-4 upshift flare / slip - " Harsh 4-3 downshifts
Replacing the broken B4 cover with a new one (PN 30651771) will remedy these symptoms.

well i saw your other post. try changing the TPS and see if that corrects it because that will screw up alot of stuff for your tranny.

P0121 - Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem

The throttle position sensor is probably either damaged, dirty, unplugged, or dead. It's located on the engine. Find the throttle body - the TPS will be the little box on the side of the throttle body - it measures how far open the throttle is, and tells the computer so the computer knows how to direct the car's driving parameters (shift points, fueling, etc).